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ELECTRICAL SYSTEMS CONTENTS

Page

CONTENTS

9/26/96 7 - 1

THEORY OF OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7-4ELECTRICAL THEORY OF OPERATION INFORMATION . . . . . . . . . . . . . . . . . . 7-4COMPONENT LOCATION INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-4IGNITION SYSTEM (ENGINE RUNNING) - 240/245/260/265 . . . . . . . . . . . . . . . . 7-8IGNITION GROUND SYSTEM (ENGINE OFF) - 240/245/260/265 . . . . . . . . . . . . 7-9IGNITION SYSTEM - 285/320 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-10CRANKING SYSTEM - 240/245/260/265/285/320 . . . . . . . . . . . . . . . . . . . . . . . . 7-12CHARGING SYSTEM - 240/245/260/265/285/320 . . . . . . . . . . . . . . . . . . . . . . . 7-13PTO SYSTEM (OFF) - 240/245/260/265/285/320 . . . . . . . . . . . . . . . . . . . . . . . . 7-14PTO SYSTEM (ON) - 240/245/260/265/285/320 . . . . . . . . . . . . . . . . . . . . . . . . . 7-15LOW FUEL WARNING SYSTEM - 240/245 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-16LOW FUEL WARNING SYSTEM - 260/265 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-17LOW FUEL WARNING SYSTEM - 285/320 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-18LOW OIL PRESSURE WARNING SYSTEM - 260/265 . . . . . . . . . . . . . . . . . . . . 7-19LOW OIL PRESSURE WARNING SYSTEM - 285/320 . . . . . . . . . . . . . . . . . . . . 7-20COOLANT TEMPERATURE WARNING SYSTEM - 285/320 . . . . . . . . . . . . . . . 7-21COOLANT TEMPERATURE LAMP CHECK SYSTEM - 285/320 . . . . . . . . . . . . 7-22HOURMETER SYSTEM - 260/265 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-23HOURMETER SYSTEM - 285/320 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-24FUEL SHUT-OFF SOLENOID SYSTEM - 240/245/260/265 . . . . . . . . . . . . . . . . . 7-25HEADLIGHT SYSTEM - 240/245/260/265/285/320 . . . . . . . . . . . . . . . . . . . . . . . 7-26FUEL INJECTION CIRCUIT OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-27FUEL INJECTION MODULE CIRCUIT OPERATION . . . . . . . . . . . . . . . . . . . . . . 7-27BATTERY VOLTAGE SENSING CIRCUIT OPERATION . . . . . . . . . . . . . . . . . . . 7-30STARTER VOLTAGE SENSING CIRCUIT OPERATION . . . . . . . . . . . . . . . . . . . 7-30THROTTLE SENSOR CIRCUIT OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-32ENGINE SPEED CIRCUIT OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-32COOLANT AND AIR TEMPERATURE SENSOR CIRCUIT OPERATION . . . . . . 7-34ALTITUDE COMPENSATION SWITCH CIRCUIT (OPTIONAL) . . . . . . . . . . . . . 7-34FUEL PUMP CIRCUIT OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-36FUEL INJECTOR CIRCUIT OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-36

ELECTRICAL SYSTEM DIAGNOSIS . . . . . . . . . . . . . . . . . . . . . . . . .7-38TESTING THE ELECTRICAL SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-38FUEL INJECTION TROUBLESHOOTING CHART . . . . . . . . . . . . . . . . . . . . . . . 7-38CRANKING CIRCUIT TEST POINTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-39MAGNETO IGNITION AND IGNITION SWITCH SYSTEM GROUND TEST POINTS - 240/245/260/265 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-41IGNITION SAFE RUN SYSTEM TEST POINTS - 240/245/260/265 . . . . . . . . . . 7-43IGNITION SYSTEM TEST POINTS - 285/320 . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-45CHARGE SYSTEM TEST POINTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-50PTO CIRCUIT TEST POINTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-52LOW FUEL INDICATOR CIRCUIT TEST POINTS - 240/245 . . . . . . . . . . . . . . . . 7-54HEADLIGHT CIRCUIT TEST POINTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-56LOW OIL PRESSURE INDICATOR LIGHT SYSTEM TEST POINTS - 260/265 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-58

CONTENTS CONTINUED ELECTRICAL SYSTEMS

7 - 2 9/26/96

Page

ELECTRICAL SYSTEM DIAGNOSIS—CONTINUEDLOW FUEL INDICATOR CIRCUIT TEST POINTS - 260/265 . . . . . . . . . . . . . . . . 7-60HOURMETER CIRCUIT TEST POINTS - 260/265 . . . . . . . . . . . . . . . . . . . . . . . . 7-62LOW OIL PRESSURE INDICATOR LIGHT CIRCUIT TEST POINTS - 285/320 . 7-64HOURMETER CIRCUIT TEST POINTS - 285/320 . . . . . . . . . . . . . . . . . . . . . . . . 7-66LOW FUEL INDICATOR CIRCUIT TEST POINTS - 285/320 . . . . . . . . . . . . . . . . 7-68COOLANT TEMPERATURE INDICATOR CIRCUIT TEST POINTS - 285/320 . . . 7-70COOLANT TEMPERATURE BULB CHECK CIRCUIT TEST POINTS - 285/320 . 7-72FUEL SHUT-OFF SOLENOID TEST POINTS - 240/245/260/265 . . . . . . . . . . . . 7-74FUEL INJECTION MODULE CIRCUIT VOLTAGE TEST . . . . . . . . . . . . . . . . . . . 7-76FUEL PUMP CIRCUIT VOLTAGE TEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-78FUEL INJECTOR CIRCUIT VOLTAGE TEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-81BATTERY VOLTAGE SENSING CIRCUIT VOLTAGE TEST . . . . . . . . . . . . . . . . . 7-83STARTER VOLTAGE SENSING CIRCUIT VOLTAGE TEST . . . . . . . . . . . . . . . . . 7-85THROTTLE SENSOR CIRCUIT VOLTAGE TEST . . . . . . . . . . . . . . . . . . . . . . . . 7-87ENGINE SPEED CIRCUIT VOLTAGE TEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-89COLLANT TEMPERATURE SENSOR CIRCUIT VOLTAGE TEST . . . . . . . . . . . . 7-91AIR TEMPERATURE SENSOR CIRCUIT VOLTAGE TEST . . . . . . . . . . . . . . . . . 7-93COMMON CIRCUIT TESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-95BATTERY TEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-95CHARGE BATTERY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-96LOAD TEST BATTERY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-96REGULATED VOLTAGE OUTPUT TEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-96UNREGULATED VOLTAGE OUTPUT TEST - 240/245/260/265 . . . . . . . . . . . . . 7-97UNREGULATED VOLTAGE OUTPUT TEST - 285/320 . . . . . . . . . . . . . . . . . . . . 7-97TEST STATOR RESISTANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-97TEST STARTED SOLENOID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-98TEST STARTER AMP DRAW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-98TEST STARTER NO-LOAD AMPERAGE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-99TEST STARTER NO-LOAD RPM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-99ADJUST IGNITION COIL AIR GAP - FC420V AND FC540V . . . . . . . . . . . . . . . . 7-99TEST IGNITION COIL - FC420V AND FC540V . . . . . . . . . . . . . . . . . . . . . . . . . 7-100IGNITION MODULE TEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-100PULSER COIL TEST - FD590V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-100IGNITION COIL TESTS - FD590V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-101SPARK PLUG CAP TEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-101SPARK TEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-102ADJUST SPARK PLUG GAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-102TEST KEY SWITCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-103TEST FLYWHEEL MAGNET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-103TEST FUEL SHUT-OFF SOLENOID - FC420V AND FC540V . . . . . . . . . . . . . . 7-103TEST LOW FUEL SWITCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-104TEST TRANSMISSION NEUTRAL SWITCH - HYDROSTATIC TRANSMISSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-104ADJUST TRANSMISSION NEUTRAL SWITCH - HYDROSTATIC TRANSMISSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-104

9/26/96 7 - 3

ELECTRICAL SYSTEMS CONTENTS CONTINUED

Page

ELECTRICAL SYSTEM DIAGNOSIS—CONTINUEDTEST TRANSMISSION NEUTRAL SWITCH - GEAR TRANSMISSION . . . . . . 7-104TEST PTO SWITCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-105TEST PTO CLUTCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-105TEST RELAY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-105ADJUST ELECTRIC PTO CLUTCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-105TEST HEADLIGHT SWITCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-106TEST SEAT SWITCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-106THROTTLE SENSOR TEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-106THROTTLE SENSOR ADJUSTMENT - 285 FUEL INJECTED . . . . . . . . . . . . . 7-107AIR TEMPERATURE SENSOR TEST - 285 FUEL INJECTED . . . . . . . . . . . . . 7-107COOLANT TEMPERATURE SENSOR TEST - 285 FUEL INJECTED . . . . . . . 7-107TEST FUEL PUMP OR FUEL INJECTION MODULE RELAY - 285 FUEL INJECTED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-108FUEL INJECTOR TEST - 285 FUEL INJECTED . . . . . . . . . . . . . . . . . . . . . . . . 7-108TEST DIODE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-108TEST GROUND CIRCUIT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-109

ELECTRICAL SYSTEM SCHEMATICS . . . . . . . . . . . . . . . . . . . . . . . 7-110

7 - 4 9/26/96

THEORY OF OPERATION ELECTRICAL SYSTEMS

THEORY OF OPERATION

ELECTRICAL THEORY OF OPERATION INFORMATIONThis group divides the electrical system into individualcircuits by function. Each circuit has been isolated fromthe main wiring schematic and only shows the compo-nents that are used in that circuit. The theory of opera-tion story explains: function of the circuit, operationconditions, components used, and current flow.The circuit schematic that accompanies each theorystory is drawn in the operating condition with the batteryor power circuit on top and the ground circuit on the bot-tom. Color is used to identify different sub-circuits. Thecolor used is not necessarily the color of the wire lead.

COMPONENT LOCATION INFORMATIONUse the drawings when troubleshooting an electricalproblem to help locate the electrical components to betested.

WIRE COLOR CODEBlu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BlueBlu/Black . . . . . . . . . . . . . . . . . . . . . . . . . . . Blue/BlackBlu/Red . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Blue/RedBlk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BlackBlk/Wht. . . . . . . . . . . . . . . . . . . . . . . . . . . . Black/WhiteBlk/Yel . . . . . . . . . . . . . . . . . . . . . . . . . . . Black/YellowBrn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . BrownBrn/Wht . . . . . . . . . . . . . . . . . . . . . . . . . . Brown/WhiteBrn/Yel . . . . . . . . . . . . . . . . . . . . . . . . . . .Brown/YellowClr. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ClearDk Blu. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Dark BlueDk Brn/Lt Grn . . . . . . . . . . . . . Dark Brown/Light GreenDk Brn/Red. . . . . . . . . . . . . . . . . . . . . Dark Brown/RedDk Brn/Yel . . . . . . . . . . . . . . . . . . . Dark Brown/YellowDk Grn . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dark GreenGrn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GreenGry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .GrayLt Blue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Light BlueLt Grn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Light GreenOrg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OrangeOrg/Wht . . . . . . . . . . . . . . . . . . . . . . . . . Orange/WhitePnk. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PinkPur . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PurplePur/Blk . . . . . . . . . . . . . . . . . . . . . . . . . . . Purple/BlackPur/Wht . . . . . . . . . . . . . . . . . . . . . . . . . . Purple/WhiteRed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RedRed/Blk. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Red/BlackRed/Blu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Red/BlueRed/Wht . . . . . . . . . . . . . . . . . . . . . . . . . . . . Red/WhiteRed/Yel. . . . . . . . . . . . . . . . . . . . . . . . . . . . .Red/YellowTan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .TanWht. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . WhiteWht/Blk. . . . . . . . . . . . . . . . . . . . . . . . . . . . White/BlackWht/Blu. . . . . . . . . . . . . . . . . . . . . . . . . . . . .White/BlueWht/Red . . . . . . . . . . . . . . . . . . . . . . . . . . . . White/RedYel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . YellowYel/Blk . . . . . . . . . . . . . . . . . . . . . . . . . . . Yellow/BlackYel/Red. . . . . . . . . . . . . . . . . . . . . . . . . . . . .Yellow/RedYel/Wht . . . . . . . . . . . . . . . . . . . . . . . . . . . Yellow/White

9/26/96 7 - 5

ELECTRICAL SYSTEMS THEORY OF OPERATION

M79560

7 - 6 9/26/96


M79561

9/26/96 7 - 7


M79562

7 - 8 9/26/96


IGNITION SYSTEM (ENGINE RUNNING) - 240/245/260/265FUNCTION:To prevent grounding the magneto type ignition circuitproviding:

1. The operator is on the seatOR

2. The transmission is in “neutral” and the PTO is “off”

MAJOR COMPONENTS:Key Switch Ignition RelaySeat Switch Ignition ModulePTO Switch Ignition CoilTransmission switch Spark Plug

CIRCUITS:(O) Power Circuit - Supplies power to the sear circuitand safety circuit when the key is in the “start” or “run”position.(P) Seat Circuit - Energizes the ignition relay when theoperator is on the seat.(Q) Safety Circuit - Energizes the ignition relay when thetransmission is in “neutral” and the PTO is “off”.(R) Ignition Circuit - Is not grounded as long as the igni-tion relay is energized. If the seat circuit and safety cir-cuit are off at the same time, the ignition circuit will go toground across terminal 30 of the ignition relay.(S) Ground Circuit - Provides a path to ground for the ig-nition relay.

S1

A

M

S2

B

G

I

OFF

RUN

START

OFF

ON

IGNITION SYSTEM (ENGINE RUNNING)240-245-260-265

A

F

C

B

FUSIBLELINK

20 AMPFUSE

O POWER CIRCUIT

S GROUND CIRCUIT

GTRANS.

NEUTRALSWITCH

I

PTOSWITCH

BATTERY

STARTER

RED

BLK

PUR

YEL/BLK

YEL/RED

P SEAT CIRCUIT

Q SAFETY CIRCUIT

R IGNITION CIRCUIT

RED

M87A 87 86

8530

YEL/BLK

KEY SWITCHE

MXC70751

D

87A 87 86

8530

YEL/BLK

IGNITIONMODULE

K

IGNITIONCOIL

L

SPARKPLUG

M

WHT

WHT

CLR

CLR

IGNITIONRELAY

PNK

PUR

PTORELAY N

SEATSWITCH

H

J

PUR/BLK

ON

OFF

BLK

NEUTRAL

N

GEAR

9/26/96 7 - 9


IGNITION GROUND SYSTEM (ENGINE OFF) - 240/245/260/265FUNCTION:To stop the engine when the operator desires bygrounding the magneto type ignition.MAJOR COMPONENTS:Key Switch

CIRCUITS:(J) Power Circuit - Stops at the key switch when the keyis “off”.(K) Ground Circuit - Provides a path to ground for themagneto type ignition when the key is “off”.

S1

A

M

S2

B

G OFF

RUN

START

WHT

BLK

87A87 86

8530

WHT

WHT

BLK

BLK

RED

RED

POWER CIRCUIT

GROUND CIRCUITMXC70752

J

K

IGNITIONGCOIL

IGNITIONF

RELAY

IGNITIONH

MODULE

SPARKI

PLUG

BATTERYB

STARTERC

M

KEYE SWITCH

DFUSIBLE

LINK

A IGNITION GROUND SYSTEM (ENGINE OFF)240-245-260-265

7 - 10 9/26/96


IGNITION SYSTEM - 285/320FUNCTION:Provides battery voltage for the battery coil type ignitionsystem providing:

1. The operator is on the seatOR

2. The transmission is in “neutral” and the PTO is “off”.

MAJOR COMPONENTS:BatteryKey SwitchIgnition RelaySeat SwitchTransmission SwitchPTO SwitchIgnition ModulePulsar CoilsIgnition CoilsSpark Plugs

CIRCUITS:(R) Power Circuit - Provides power to the ignition supplycircuit, seat circuit, and safety circuit when the key is inthe “start” or “run” position.(T) Seat Circuit - Energizes the ignition relay when theoperator is on the seat.(U) Safety Circuit - Energizes the ignition relay when thetransmission is in “neutral” and the PTO is “off”.(S) Ignition Supply Circuit - Provides power to the igni-tion circuit providing the ignition relay is energized.(V) Battery Coil Ignition Circuit - Produces the spark forignition and controls the timing of the spark.(W) Ground Circuit - Provides a path to ground for theignition relay and ignition module.

9/26/96 7 - 11


IGNITION GROUND SYSTEM - 285/320

BLK

/YEL

S1

A

M

S2

B

GNEUTRAL

INGEAR

OFF

RUN

START

OFF

ON

IGN

ITION

SYSTEM - 285-320

A

F

C

B

FUSIB

LELIN

K

20 AM

PFU

SE

RPO

WER

CIR

CU

IT

XG

RO

UN

D C

IRC

UIT

KTR

AN

SMISSIO

NN

EUTR

AL

SWITC

HJPTO

SWITC

H

BA

TTERY

STAR

TER

RED

BLK

PUR

YEL/BLK

YEL/RED

TSEA

T SWITC

H C

IRC

UIT

USA

FETY CIR

CU

IT

SIG

NITIO

N SU

PPLY CIR

CU

IT

RED

M87A

8786

8530

KEY SW

ITCH

E

MX

C70753

D

87A87

868530

YEL/BLK

IGN

ITION

MO

DU

LEL

RIG

HT

IGN

ITION

CO

ILP

SPAR

KPLU

GS

Q

CLR

IGN

ITION

RELA

YPN

K

PUR

PTOR

ELAY

H

SEAT

SWITC

HI

GON

OFF

YEL/BLK

WH

T

LEFTIG

NITIO

NC

OIL

O

PNK

YEL/W

HT

YEL/W

HT

YEL/W

HT

BLK

WH

T

OR

G/

WH

TG

RN

/W

HT

PUR

/B

LK

YEL

PNK

LEFTPU

LSAR

CO

ILM

RIG

HT

PULSA

RC

OIL

N

PNK

YEL/BLK

BLK

BLK

VB

ATTER

Y IGN

ITION

CO

IL CIR

CU

IT

WPU

LSAR

CO

IL CIR

CU

IT

WH

T/B

LU

7 - 12 9/26/96


CRANKING SYSTEM - 240/245/260/265/285/320FUNCTION:To energize the starter motor.MAJOR COMPONENTS:BatteryKey SwitchTransmission SwitchStart RelayStarter

CIRCUITS:(J) Power Circuit- With the key in start position power issupplied to the safe start circuit.(K) Safe Start Circuit - With the PTO “off” and transmis-sion in neutral the starter relay is energized.(L) Solenoid Engaging Circuit - When the starter relay isenergized battery voltage flows through the relay andenergizes the starter solenoid.(M) Starter Power Circuit - When the starter solenoid isenergized battery voltage is supplied to the starter mo-tor.(N) Ground Circuit - Provides a path to ground for thesafe start circuit.

S1

A

M

S2

B

G

NEUTRAL

IN

GEAR

OFF

RUN

START

OFF

ON

CRANKING SYSTEM240-245-260-265-285-320

A

G

C

B

F

FUSIBLELINK

20 AMPFUSE

J POWER CIRCUIT

N GROUND CIRCUIT

I

TRANSMISSIONNEUTRALSWITCH

H

PTOSWITCH

BATTERY

STARTER

RED

BLK

BLK

PUR

YEL/BLK

YEL/RED

K SAFE START CIRCUIT

L SOLENOID ENGAGING CIRCUIT

M STARTER POWER CIRCUIT

RED

M

87A 87 85

8630

STARTERRELAY

FUSIBLELINK

PUR

YEL/BLK

PUR/WHT

KEYSWITCH

E

PUR

RED

MXC70750

D

D

9/26/96 7 - 13


CHARGING SYSTEM - 240/245/260/265/285/320FUNCTION:To maintain battery voltage and warn the operator if thecharging system is not functioning.

MAJOR COMPONENTS:BatteryRegulator/RectifierStatorLamp

CIRCUITS:(J) Stator AC Circuit - Provides alternating current to theregulator/rectifier.(K) Voltage Monitor Circuit - Senses battery voltage atthe regulator/rectifier.(L) Battery Charging Circuit - Routes DC current fromthe regulator/rectifier to the battery.(M) Discharge Lamp Circuit - If the stator output is lostthe regulator/rectifier provides battery voltage throughthis circuit to the discharge lamp.(N) Ground Circuit - Provides a path to ground for theregulator/rectifier and the discharge lamp.

S1

A

M

S2

B

G OFF

RUN

START

CHARGING SYSTEM240-245-260-265-285-320

A

F

C

B

FUSIBLELINK 20 AMP

FUSE

N GROUND CIRCUIT

BATTERY

STARTER

RED

BLK

YEL/RED

RED

M

YEL/BLK

KEY SWITCHE

MXC70754

D

M DISCHARGE LAMP CIRCUIT

L BATTERY CHARGING CIRCUIT

K VOLTAGE MONITOR CIRCUIT

J STATOR AC CIRCUIT

RECTIFIERREGULATOR

G

RED

BRN/YEL

BRN/WHT

BRN

BLK

BLK

STATOR

DISCHARGELAMP

H

I

7 - 14 9/26/96


PTO SYSTEM (OFF) - 240/245/260/265/285/320FUNCTION:

1. To stop current to the PTO clutch.2. To make sure that the operator is on the seat and

the PTO is off before current is made available to the clutch side of the PTO switch.

MAJOR COMPONENTS:Seat SwitchIgnition RelayPTO SwitchPRO Relay

CIRCUITS:(K) Power Circuit - Provides current to ignition relay cir-cuit, seat circuit, and PTO safety circuit.(L) Seat Circuit - Energizes the ignition relay if the oper-ator is on the seat.(M) PTO Safety Circuit - Energizes the PTO safety cir-cuit if the PTO is “off”.(N) Ignition Relay Circuit - Provides power to the PTOrelay.(O) PTO Relay Circuit - Provides power to the clutchside of the PTO switch.(P) Ground Circuit - Provides a path to ground for the ig-nition relay and PTO relay.

S1

A

M

S2

B

G OFF

RUN

START

OFF

ON

PTO SYSTEM (OFF)240-245-260-265-285-320

A

F

C

B

FUSIBLELINK 20 AMP

FUSE

K POWER CIRCUIT

P GROUND CIRCUIT

I

PTOSWITCH

BATTERY

STARTER

RED

BLK

YEL/BLK

L SEAT CIRCUIT

M

KEYSWITCH

E

MXC70755

87A 86

8530

YEL/BLK

CLR

IGNITIONRELAY

PNK

87A 87 86

8530

PTORELAY

H

SEATSWITCH

J

G

O IGNITION RELAY CIRCUITM P.T.O. SAFETY CIRCUIT

N P.T.O. RELAY CIRCUIT

87

RED

D

BLU

BLK

PNK

CLR

PUR/WHT

YEL/RED

YEL/BLK

YEL/BLK

BLK

CLR

ON

OFF

9/26/96 7 - 15


PTO SYSTEM (ON) - 240/245/260/265/285/320FUNCTION:To maintain power to the PTO clutch providing the oper-ator is on the seat.MAJOR COMPONENTS:Seat SwitchIgnition RelayPTO SwitchPTO RelayPTO Clutch

CIRCUITS:(L) Power Circuit - Provides power to the PTO circuitand seat circuit.(M) Seat Circuit - Keeps the ignition relay energizedproviding the operator is on the seat.(N) PTO Circuit - Provides power to the PTO clutch.When the PTO switch is in the “on” position the PTO re-lay remains energized by routing current from terminal30 to terminal 86. If the operator gets off the seat thengets back on the PTO relay will have de-energized. Tore-energize the PTO relay again the PTO switch mustbe turned off.(O) Ground Circuit - Provides a path to ground for theignition relay and PTO relay.

M

S1

A

M

S2

B

G

ON

OFF

OFF

RUN

START

OFF

ON

87A 87 86

8530

87A 87 86

8530

PTO SYSTEM (ON)240-245-260-265-285-320

A

E

D

F

C

L

H

B

G

POWER CIRCUIT

KEY SWITCH

FUSIBLELINK

20 AMPFUSE

N SEAT CIRCUIT

M P.T.O. CIRCUIT

O GROUND CIRCUIT

P.T.O.RELAY

IGNITIONRELAY

K

SEATSWITCH

IPTO

SWITCH

JPTO

CLUTCH

BATTERY

STARTER

RED

REDPNK

BLK BLKBLK

BLK

BLU

BLU

PNK

YEL/BLK

YEL/BLK

YEL/BLK

YEL/RED

CLR

MXC70756

7 - 16 9/26/96


LOW FUEL WARNING SYSTEM - 240/245FUNCTION:To illuminate the low fuel lamp on the dash if the tractorfuel supply is nearing empty.MAJOR COMPONENTS:Low Fuel LampLow Fuel Switch

CIRCUITS:(I) Power Circuit - Provides power to the low fuel lamp.(J) Ground Circuit - Provides a path to ground when thefloat type switch closes.

S1

A

M

S2

B

G OFF

RUN

START

A

C

B

FUSIBLELINK

10 AMPFUSE

POWER CIRCUIT

BATTERY

STARTER

RED

BLK

YEL/RED

GROUND CIRCUIT

RED

M

KEYSWITCH

E

MXC70757

D

LOW FUEL WARNING SYSTEM240-245

F

HLOWFUEL

SWITCH

GLOWFUELLIGHT

FULL

EMPTY

I

J

YEL

BLK

9/26/96 7 - 17




S1

A

M

S2

B

G OFF

RUN

START

A

C

B

FUSIBLELINK

10 AMPFUSE

BATTERY

RED

BLK

YEL/RED

RED

M

KEY SWITCHE

MXC70760

D

LOWFUELLAMP

I

OILPRESSURE

LAMP

HOURMETER

STARTER EMPTY

FULL

POWER CIRCUIT

GROUND CIRCUIT

K

L

J

H

LOWFUEL

SWITCH

G

F

YELYEL

YEL

BLK

BLK/WHT

LOW FUEL WARNING SYSTEM260-265

7 - 18 9/26/96




S1

A

M

S2

B

G OFF

RUN

START

LOW FUEL WARNING SYSTEM - 285A

F

C

B

FUSIBLELINK

L POWER CIRCUIT

BATTERY

STARTER

RED

BLK

M

KEY SWITCH E

MXC70764 M GROUND CIRCUIT

RED

D

10 AMPFUSE

YEL/RED

YEL

GHOURMETER

H

YEL

COOLANTTEMPLAMP

OILPRESSURE

LAMP

LOWFUELLAMP

LOWFUEL

SWITCH

IJ

K

YEL

BLK

BLK/WHT

9/26/96 7 - 19


LOW OIL PRESSURE WARNING SYSTEM - 260/265FUNCTION:To illuminate a lamp on the dash if engine oil pressureis lower than minimum operation pressure.MAJOR COMPONENTS:Oil Pressure LampOil Pressure Switch

CIRCUITS:(J) Power Circuit - Provides current to the oil pressurelamp.(K) Ground - The switch grounds the power circuit to theengine block when it closes.

S1

A

M

S2

B

G OFF

RUN

START

LOW OIL PRESSURE WARNING SYSTEM260-265

A

F

C

B

FUSIBLELINK

J POWER CIRCUIT

BATTERY

STARTER

RED

BLK

M

KEY SWITCHE

MXC70759 K GROUND CIRCUIT

RED

D

10 AMPFUSE

YEL/RED

YEL

GHOURMETER

YEL

OILPRESSURE

LAMP

OILPRESSURE

SWITCH

H

ITAN

7 - 20 9/26/96


LOW OIL PRESSURE WARNING SYSTEM - 285/320FUNCTION:To illuminate a lamp on the dash if engine oil pressureis lower than minimum operating pressure.MAJOR COMPONENTS:Oil Pressure LampOil Pressure Switch

CIRCUITS:(K) Power Circuit - Provides current to the oil pressurelamp.(L) Ground - The switch grounds the power circuit to theengine block when it closes.

S1

A

M

S2

B

G OFF

RUN

START

LOW OIL PRESSURE WARNING SYSTEM - 285-320A

F

C

B

FUSIBLELINK

K POWER CIRCUIT

BATTERYSTARTER

RED

BLK

M

KEY SWITCH E

MXC70762L GROUND CIRCUIT

RED

D

10 AMPFUSE

YEL/RED

YEL

GHOURMETERH

YEL

COOLANTTEMPLAMP

OILPRESSURE

LAMP

OILPRESSURE

SWITCH

I

J

BLK

YEL

TAN

BLURED

9/26/96 7 - 21


COOLANT TEMPERATURE WARNING SYSTEM - 285/320FUNCTION:To illuminate a lamp on the dash if engine coolant tem-perature exceeds normal operating temperature.MAJOR COMPONENTS:Coolant Temperature LampCoolant Temperature Switch

CIRCUITS:(J) Power Circuit - Provides power to the coolant tem-perature lamp.(K) Ground Circuit - The coolant temperature switchgrounds the power circuit to the engine block when itcloses.

S1

A

M

S2

B

G OFF

RUN

START

FUSIBLELINK

10 AMPFUSE

POWER CIRCUIT

BATTERY

STARTER

RED

BLK

YEL/RED

J

GROUND CIRCUIT

RED

M

KEYSWITCH

E

MXC70765

COOLANT TEMPERATURE WARNING SYSTEM - 285-320

COOLANTTEMP

SWITCH

ORG/WHT

K

COOLANTTEMP LAMP

HOURMETER

A

B

D

I

C

HF

G

YELYEL

7 - 22 9/26/96


COOLANT TEMPERATURE LAMP CHECK SYSTEM - 285/320FUNCTION:To illuminate the coolant temperature lamp when thekey is in the “start” position.MAJOR COMPONENTS:Coolant Temperature LampPTO SwitchStarter RelayTransmission Neutral SwitchCoolant Temperature Lamp Relay

CIRCUITS:(O) Power Circuit - Provides power to the safe start cir-cuit and lamp test circuit.(P) Safe Start Circuit - Routes power to the coolant relayswitch.(Q) Coolant Relay Circuit - Energizes the coolant tem-perature relay.(R) Lamp Test Circuit - Provides power to the coolanttemperature relay.(S) Ground Circuit - Provides a path to ground for thecoolant temperature lamp and the lamp test circuit.

S1

A

M

S2

B

G OFF

RUN

START

OFF

ON

COOLANT TEMPERATURE LAMP CHECK SYSTEM - 285-320A

F

C

B

FUSIBLELINK

20 AMPFUSE

O POWER CIRCUIT

BATTERY

STARTER

RED

BLK

P SAFE START CIRCUIT

M

KEYSWITCH

E

MXC70766

87A

86

85

30

87A8786

85 30

R LAMP TEST CIRCUIT

S GROUND CIRCUIT

87

RED

D

I10 AMPFUSE

NEUTRAL

IN

GEAR

Q COOLANT RELAY CIRCUIT

TRANSNEUTRALSWITCH

PUR

YEL/REDYEL/RED

YEL/BLKYEL

JHOURMETER

LCOOLANT

TEMPSWITCH

YEL/BLK

YEL

ORG/WHT

COOLANTTEMPLAMP K

PUR/BLK

ORG/WHT

PUR

COOLANTTEMPLAMP

RELAY

MPTO

SWITCH

G

H

BLKBLK

STARTERRELAY

N

PUR

9/26/96 7 - 23


HOURMETER SYSTEM - 260/265FUNCTION:To records the number of hours the key is in the “run”position.MAJOR COMPONENTS:Key SwitchHourmeter

CIRCUITS:(H) Power Circuit - Provides power to the hourmeterwhen the key is in the “run” position.(I) Ground Circuit - Provides a path to ground for thehourmeter.

S1

A

M

S2

B

G OFF

RUN

START

A

C

B

FUSIBLELINK

10 AMPFUSE

POWER CIRCUITBATTERY

STARTER

RED

BLK

YEL/RED

I GROUND CIRCUIT

RED

M

KEY SWITCHE

MXC70761

D

HOURMETER G

HOURMETER SYSTEM260-265

H

F

BLK

YEL

7 - 24 9/26/96


HOURMETER SYSTEM - 285/320FUNCTION:To record the number of hours the key is in the “run” po-sition.MAJOR COMPONENTS:Key SwitchHourmeter

CIRCUITS:(H) Power Circuit - Provides power to the hourmeterwhen the key is in the “run” position.(I) Ground Circuit - Provides a path to ground for thehourmeter.

G

S1

A

M

S2

B

G OFF

RUN

START

A

C

B

FUSIBLELINK

10 AMPFUSE

POWER CIRCUIT

BATTERY

STARTERRED

BLK

YEL/RED

I GROUND CIRCUIT

RED

M

MXC70763

D

HOURMETER SYSTEM - 285-320KEY

SWITCH

HOURMETER

H

F

E

YEL

BLK

9/26/96 7 - 25


FUEL SHUTOFF SOLENOID SYSTEM - 240/245/260/265FUNCTION:To energize the fuel shutoff solenoid when the key is inthe “start” or “run” position.MAJOR COMPONENTS:Key SwitchFuel Shutoff Solenoid

CIRCUITS:(H) Power Circuit - provides power to the fuel shutoff so-lenoid when the key is in the “start” or “run” position.(I) Ground Circuit - The fuel shutoff solenoid body isgrounded to the carburetor.

S1

A

M

S2

B

G OFF

RUN

START

FUEL SHUTOFF SOLENOID SYSTEM240-245-260-265

A

FC

B

FUSIBLELINK

H POWER CIRCUIT

BATTERY

STARTERRED M

KEY SWITCH E

MXC70767I GROUND CIRCUIT

RED

D

20 AMPFUSE

YEL/RED

YEL/BLK

FUELSHUTOFFSOLENOID

G

7 - 26 9/26/96


HEADLIGHT SYSTEM - 240/245/260/265/285/320FUNCTION:To illuminate the headlights if the operator selects.MAJOR COMPONENTS:Light SwitchHeadlights

CIRCUITS:(I) Power Circuit - Provides power to the headlightswhen the switch is turned on.(J) Ground Circuit - Provides a path to ground for theheadlights.

F

S1

A

M

S2

B

G OFF

RUN

START

A

C

B

FUSIBLELINK

20 AMPFUSE

POWER CIRCUIT

BATTERY

STARTER

RED

BLK

YEL/RED

J GROUND CIRCUIT

RED

M

KEYSWITCH

E

MXC70758

D

ON

OFF

YEL/WHT

YEL/WHT

YEL/WHT

LIGHTSWITCHG

HEADLIGHTSH

HEADLIGHT SYSTEM240-245-260-265-285-320

I

BLK

YEL/BLK

YEL/BLK

9/26/96 7 - 27


FUEL INJECTION CIRCUIT OPERATIONThe FD590V fuel injected engine uses a digital fuel in-jection system to control fuel delivery to the injector. Thefuel injection system is energized when the key switchis in the ON position.

The fuel injection system consists of:• sensor circuit• fuel injection module circuit• fuel control circuit

The sensor circuit contains sensors or circuits that mon-itor engine operation conditions. These sensors or cir-cuit send digital signals to a computer in the fuelinjection module circuit. The computer processes thesesignals and determines the correct amount of fuel to in-ject to match the present engine operating conditions.After the amount of fuel to inject is determined, the com-puter energizes the fuel control circuit to inject the fuel.

The sensor circuit consists of:• throttle sensor• air temperature sensor• coolant temperature sensor• starter voltage circuit• engine speed circuit• battery voltage circuit• altitude compensation switch (optional)

The fuel injection module circuit consists of:• fuel injection module• fuel injection module relay

The fuel control circuit consists of:• fuel injector• fuel pump• fuel pump relay

FUEL INJECTION MODULE CIRCUIT OPERATIONThe fuel injection module circuit provides power to thefuel injection module (G) through the ignition circuit. Theignition relay must be energized for the fuel injectionmodule to operate. In order for fuel injection module tooperate, the operator must be ON the seat or the trans-mission must be in NEUTRAL and the PTO must beOFF. If current flow to the ignition circuit is stopped, cur-rent flow to the fuel injection module is also stopped.This shuts off ignition and fuel at the same time.

The fuel injection module circuit consists of:• battery• fusible link• fuel injection module• fuel injection module relay• ignition circuit

Current flows from the battery (C), through fusible link(B) to the fuel injection module relay (F) terminal 3. Current cannot flow to the fuel injection module (G) untilthe fuel injection module relay coil (terminal 2) is ener-gized. The fuel injection module relay receives energiz-ing current from the ignition relay. With the ignition relayenergized, current from the positive side of ignition coil(E) flows to the fuel injection module relay coil and en-ergizes it, closing the relay. Closing the relay sends cur-rent to the fuel injection module.The fuel injection module must have voltage for the sen-sors to operate correctly, since the fuel injection modulesends input voltage to the sensor and monitors outputvoltage or just monitors an output signal. The fuel injec-tion module receives engine operating conditions fromthe sensors and processes those sensor signals usinga computer. The computer calculates the correctamount of fuel to inject, controls fuel injector operation,and controls fuel pump operation. The fuel injectionmodule is a solid state component and cannot be re-paired or tested.

7 - 28 9/26/96


FUEL INJECTION CIRCUIT OPERATION

M

BA

TTERY

M

FUEL IN

JECTIO

N C

IRC

UITS

MX

C45336

1

SSEN

SOR

CIR

CU

ITT

FUEL IN

JECTIO

NM

OD

ULE C

IRC

UIT

UFU

EL CO

NTR

OL

CIR

CU

IT

QFR

OM

PTO R

ELAY

TERM

INA

L 872

RFR

OM

STAR

TER R

ELAY

TERM

INA

L 87

AFU

SIBLE

LINK

B

FUSIB

LELIN

KB

D

FUEL

PUM

PR

ELAY

C

1

1

235

BLK

RED

/WH

T

RED

/YEL

REDR

ED

RED

/WH

T FUEL

INJEC

TOR

H

IGN

ITION

MO

DU

LEI

IGN

ITION

CO

ILG

SPAR

KPLU

GF

BLK

FUEL

PUM

PE

PUR

BLK

RED

/BLK

WH

T/BLU

BLU

/BLK

RED

/YEL

RED

/B

LU

12 3

5

YEL/W

HT

BLK 2

FUEL

INJEC

TION

MO

DU

LER

ELAYJ

BLU

/RED YEL

BLK B

LU

BLK

BLK

WH

TRED

CO

OLA

NT

TEMP

SENSO

RK

AIR

TEMP

SENSO

R

L

STAR

TERN

THR

OTTLE

SENSO

RM

GR

N/

WH

T

ALTITU

DE

CO

MPEN

SATIO

NSW

ITCH

O

BLK B

LKBLKB

LK

FUEL

INJEC

TION

MO

DU

LE

P

9/26/96 7 - 29


FUEL INJECTION MODULE CIRCUIT

FUEL INJECTION MODULE CIRCUIT

MXC45340 1

H IFUEL INJECTION MODULEPOWER CIRCUIT

J GROUND CIRCUIT

KFROM PTO RELAY

TERMINAL 87

AFUSIBLE

LINKB

1

BLK

RED/YEL

RED

IGNITIONMODULE

D

IGNITIONCOIL

E

RED/YEL RED/

BLU

12

3 5

YEL/WHT

BLK

FUELINJECTION

MODULERELAY

F

BLK

FUELINJECTION

MODULEG

BATTERYC

RELAY ENGAGEMENTCIRCUIT

7 - 30 9/26/96


BATTERY VOLTAGE SENSING CIRCUIT OPERATIONThe battery voltage sensing circuit allows the fuel injec-tion module to monitor changes in battery voltage re-sulting from electrical loads or battery charging. A circuitin the fuel injection module converts varying batteryvoltage to a constant 5 or 8 volts, which is used in thesensor circuits. The sensor input voltage must be con-stant for the computer to process the sensor signalscorrectly. The fuel injection module relay must be ener-gized for the battery voltage sensing circuit to operate.

The battery voltage sensing circuit consists of:• battery• fusible link• fuel injection module relay• fuel injection module

Current flows from the battery (C), through fusible link(B) to the fuel injection module relay (F) terminal 3 andfuel injection module (H) (sensing path). When the fuelinjection module relay is energized (key switch ON, ig-nition relay energized), current flows to the fuel injectionmodule and energizes the battery voltage sensing cir-cuit.

STARTER VOLTAGE SENSING CIRCUIT OPERATIONThe starter voltage sensing circuit sends started sole-noid voltage to the fuel injection module, which tells thecomputer the engine is starting. Then the computer en-riches the fuel-air mixture to improve starting. The start-er voltage sensing circuit operates only when the startersolenoid is engaged and the fuel injection module relayis energized.

The starter voltage sensing circuit consists of:• batter• fusible link• fuel injection module relay• fuel injection module• starter• starting circuit

Current flows from the battery (C), through fusible link(B) to the fuel injection module relay (F) terminal 3.When the fuel injection module relay is energized (keyswitch ON, ignition relay energized), current flows to thefuel injection module (H). With the key switch turned toSTART, current from the starter (G) solenoid engagedterminal flows to the fuel injection module and energizesthe starter voltage circuit.

9/26/96 7 - 31


BATTERY AND STARTER VOLTAGE SENSING CIRCUIT

M

BATTERY

BATTERY AND STARTER VOLTAGE SENSING CIRCUIT

MXC45341

1I

FROM PTO RELAYTERMINAL 87

2J

FROM STARTER RELAYTERMINAL 87

A

FUSIBLELINKB

C

1

BLK

RED/YELRED

IGNITIONMODULE

D

IGNITIONCOILE

RED/YEL RED/

BLU

12

3 5

YEL/WHT

BLK

2

FUELINJECTION

MODULERELAY

F BLU/RED STARTERG

BLK

FUELINJECTION

MODULE

H

K FUEL INJECTIONMODULE POWER CIRCUIT

L RELAY ENGAGEMENTCIRCUIT

M BATTERY VOLTAGESENSING CIRCUIT

N STARTER VOLTAGESENSING CIRCUIT

O GROUND CIRCUIT

7 - 32 9/26/96


THROTTLE SENSOR CIRCUIT OPERATIONThe throttle sensor circuit tells the computer the positionof the throttle plate which is directly connected to thethrottle lever. The throttle sensor is installed on thethrottle body. The fuel injection module sends input volt-age to the throttle sensor and monitors output voltage todetermine throttle position. The fuel injection module re-lay must be energized for the throttle sensor circuit tooperate.

The throttle sensor circuit consists of:• battery• fusible link• fuel injection module relay• fuel injection module• throttle sensor

Current flows from the battery (C), through fusible link(B) to the fuel injection module relay (G) terminal 3. When the fuel injection module relay is energized (keyswitch ON, ignition relay energized), current flows to thefuel injection module (I) and energizes the throttle sen-sor circuit.The throttle sensor (H) uses a potentiometer that is con-nected to the throttle plate shaft. When the throttle plateshaft moves, the potentiometer resistance is varied.The fuel injection module sends input voltage to thethrottle sensor. With the throttle plate in a set position,the potentiometer has a specific resistance that variesthe voltage flowing through it to produce a specific out-put voltage. The throttle sensor output voltage flowsback to the fuel injection module computer. The comput-er uses this voltage to indicate throttle plate position.The throttle sensor voltage output increases as thethrottle plate opening increases.

ENGINE SPEED CIRCUIT OPERATIONThe engine speed circuit allows the fuel injection mod-ule to monitor engine rpm. Engine speed is picked up atthe negative terminal of the ignition coil. The fuel injec-tion module relay and the ignition circuit must be ener-gized for the engine speed circuit to operate.

The engine speed circuit consists of:• battery• fusible link• fuel injection module relay• fuel injection module• ignition coil• ignition circuit

Current flows from the battery (C), through fusible link(B) to the fuel injection module relay (G) terminal 3.When the fuel injection module relay is energized (keyswitch ON, ignition relay energized), current flows to thefuel injection module (I) and energized the enginespeed circuit.With the ignition relay energized, current from the neg-ative terminal of the ignition coil (E) flows to the fuel in-jection module. One current pulse per crankshaftrevolution is sent to the fuel injection module. The fuelinjection module uses this current pulse to determineengine rpm.

9/26/96 7 - 33


THROTTLE SENSOR AND ENGINE SPEED CIRCUIT

BATTERY

THROTTLE SENSOR AND ENGINE SPEED CIRCUIT

MXC45343 1

N OUTPUT VOLTAGECIRCUIT

O ENGINE SPEEDCIRCUIT

P GROUND CIRCUIT

JFROM PTO RELAY

TERMINAL 87

A

FUSIBLELINKB

C

1

BLK

RED/YEL

RED

IGNITIONMODULE

D

IGNITIONCOIL

E

SPARKPLUG

F

BLU/BLK

RED/YEL RED/

BLU

12

3 5

YEL/WHT

BLK

FUELINJECTION

MODULERELAY

G

BLK

WHTRED

THROTTLESENSOR

H

BLKBLK

FUELINJECTION

MODULE

I

K L RELAY ENGAGEMENTCIRCUIT

M INPUT VOLTAGECIRCUIT

FUEL INJECTIONMODULE POWER CIRCUIT

7 - 34 9/26/96


COOLANT AND AIR TEMPERATURE SENSOR CIRCUIT OPERATIONThe coolant and air temperature sensor circuits allowthe fuel injection module to monitor engine coolant andthrottle body intake air temperature. The coolant tem-perature sensor is installed in the cylinder head. The airtemperature sensor is installed in the throttle body be-tween the air cleaner and the intake manifold. The fuelinjection module relay must be energized for the coolantand air temperature sensor circuit to operate.

The coolant and air temperature circuit consists of:• battery• fusible link• fuel injection module relay• fuel injection module• coolant temperature sensor• air temperature sensor

Current flows from the battery (C), through fusible link(B) to the fuel injection module relay (F) terminal 3.When the fuel injection module relay is energized (keyswitch ON, ignition relay energized), current flows to thefuel injection module (K) and energizes the coolant andair temperature sensor circuits.The coolant and air temperature sensors (G and H) usethermistors to indicate temperature. Current from thefuel injection module flows to the sensors. The ther-mistor resistance, depending on temperature, variesthe current flow through the sensor. The fuel injectionmodule computer monitors current flow through thesensors to determine engine temperature. The resis-tance of the thermistor in the sensors decreases as thetemperature increases.

ALTITUDE COMPENSATION SWITCH CIRCUIT (OPTIONAL)The altitude compensation switch circuit allows the fuelinjection module computer to adjust the fuel-air mixturewhen the unit is operated above 1500 m (4918 ft.). Thefuel injection module relay must be energized and theunit must be operated above 1500 m (4918 ft.) for thealtitude compensation switch to operate.

The altitude compensation switch circuit consists of:• battery• fusible link• fuel injection module relay• fuel injection module• altitude compensation switch

Current flows from the battery (C), through fusible link(B) to the fuel injection module relay (F) terminal 3.When the fuel injection module relay is energized (keyswitch ON, ignition relay energized), current flows to thefuel injection module (K) and then to the altitude com-pensation switch circuit (J). When the unit is operatedbelow 1500 M (4918 ft.), the altitude compensationswitch is closed and provides a path to ground to ener-gize the circuit. When the unit is operated above 1500M (4918 ft.), the altitude compensation switch opensbreaking the path to ground which denergized the cir-cuit. This leans the fuel-air mixture for high altitude op-eration.

9/26/96 7 - 35


COOLANT AND AIR TEMPERATURE SENSOR CIRCUIT AND ALTITUDE COMPENSATION SWITCH CIRCUIT

BATTERY

COOLANT AND AIR TEMPERATURE SENSOR CIRCUITAND ALTITUDE COMPENSATION SWITCH CIRCUIT

MXC45344

1L

FROM PTO RELAYTERMINAL 87

A

FUSIBLELINKB

C

1

BLK

RED/YEL

RED

IGNITIONMODULE

D

IGNITIONCOILE

RED/YEL RED/

BLU

12

3 5

YEL/WHT

BLK

FUELINJECTION

MODULERELAY

F

YEL

BLK

BLU

BLK

BLK

WHTRED

COOLANTTEMP

SENSOR G

AIRTEMP

SENSOR

H

THROTTLESENSOR

I GRN/WHT

ALTITUDECOMPENSATION

SWITCH

J

BLKBLK

BLK

FUELINJECTION

MODULE

K

M FUEL INJECTIONMODULE POWER CIRCUIT

N RELAY ENGAGEMENTCIRCUIT

O COOLANT TEMPCIRCUIT

P AIR TEMP CIRCUIT Q ALTITUDE COMPENSATIONSWITCH CIRCUIT

R GROUND CIRCUIT

7 - 36 9/26/96


FUEL PUMP CIRCUIT OPERATIONThe fuel pump circuit allows the fuel injection modulecomputer to control operation of the fuel pump. The fuelinjection module relay and the fuel pump relay must beenergized for the fuel pump to operate. It is normal forthe fuel pump to turn on and off depending on fuelneeds.The fuel pump operates only under the following condi-tions:

• for about 5 seconds after key switch is turned ON.• when the starter solenoid is energized (start signal).• when the engine is running (engine speed signal).

When the above fuel conditions are satisfied, the fuel in-jection module computer de-energizes the fuel injectionmodule relay, which stops fuel pump operation.The fuel pump circuit consists of:

• battery• fusible link (protects fuel injection module)• fuel injection module relay• fuel injection module• fusible link (protects fuel pump)• fuel pump relay• fuel pump

Current flows from the battery (E), through fusible link(B) to the fuel injection module relay (H) terminal 3.When the fuel injection module relay is energized (keyswitch ON, ignition relay energized), current flows to thefuel injection module (K).Current from the battery also flows to fusible link (C) andfuel pump relay (D) terminal 3. Current cannot flow tothe fuel pump (F) until the fuel pump relay coil (terminal2) is energized. The fuel pump relay received energiz-ing current from the fuel injection module. When the fuelinjection module computer determines that fuel is need-ed, current from the fuel injection module flows to thefuel pump relay coil and energizes it, closing the relay.Closing the relay sends battery current to the fuel pump.When fuel conditions are satisfied, the fuel injectionmodule computer stops current flow to the fuel pump re-lay coil. The fuel pump relay opens and stops currentflow to the fuel pump.

FUEL INJECTOR CIRCUIT OPERATIONThe fuel injector circuit allows the fuel injection modulecomputer to control operation of the fuel injector. Thefuel injection module relay must be energized for thefuel injector to operate.The fuel injector circuit consists of:

• battery• fusible link (protects fuel injection module)• fuel injection module relay• fuel injection module• fusible link (protects fuel injector)• fuel injector

Current flows from the battery (E), through fusible link(B) to the fuel injection module relay (H) terminal 3.When the fuel injection module relay is energized (keyswitch ON, ignition relay energized), current flows to thefuel injection module (K).Current from the battery is available to fusible link (C),fuel injector (J) and fuel injection module. The fuel injec-tor cannot be energized until it has a path to ground.The fuel injection module computer creates a path toground to energize the fuel injector for a specific amountof time depending on engine operating conditions ob-tained from the sensors. When the fuel conditions aresatisfied, the fuel injection module computer breaks thepath to ground, which stops fuel injector operation.

9/26/96 7 - 37


FUEL PUMP AND FUEL INJECTOR CIRCUIT

BATTERY

M

FUEL PUMP AND FUEL INJECTOR CIRCUITAFUSIBLE

LINKB

FUSIBLELINKC

E

FUELPUMPRELAY

D

1

1

23

5

BLK

RED/WHT

RED/YEL

RED

RED

RED/WHT

FUELINJECTOR

J

IGNITIONMODULE

I

IGNITIONCOIL

G

BLK

FUELPUMP

F

PUR

BLK

RED/BLKWHT/BLU

RED/YEL RED/

BLU

12

3 5

YEL/WHT

FUELINJECTION

MODULERELAY

H

BLKBLK

FUELINJECTION

MODULE

K

MXC45355 1

P FUEL PUMP RELAYENGAGEMENT CIRCUIT Q FUEL INJECTOR CIRCUIT R GROUND CIRCUIT

LFROM PTO RELAY

TERMINAL 87

M N FUEL INJECTION MODULERELAY ENGAGEMENT CIRCUIT

O FUEL PUMPPOWER CIRCUIT

FUEL INJECTION MODULEPOWER CIRCUIT

7 - 38 9/26/96

ELECTRICAL SYSTEM DIAGNOSIS ELECTRICAL SYSTEMS

ELECTRICAL SYSTEM DIAGNOSIS

TESTING THE ELECTRICAL SYSTEMUse the following steps when troubleshooting an elec-trical problem:

1. Visually inspect electrical system.2. Perform Operational Checkout Procedure to verify

problem circuit.3. Read theory of operation for problem circuit.4. Perform circuit voltage test.5. Perform component test.

FUEL INJECTION TROUBLESHOOTING CHARTPROBLEM SOLUTION

Fuel Pump Does Not Run With Key Switch in ON Position. . . . . . . . . . . . . . . . . GO TO A

Fuel Pump Does Not Run With Key Switch in START Position. . . . . . . . . . . . . . GO TO B

Engine Will Not Start . . . . . . . . . . . . . . . . . . . GO TO CEngine Starts But Runs Rough . . . . . . . . . . . GO TO D

A—FUEL PUMP DOES NOT RUN WITH KEYSWITCH IN ON POSITION

1. Test fuel pump circuit voltage.2. Test fuel injection module circuit voltage.

B—FUEL PUMP DOES NOT RUN WITH KEYSWITCH IN START POSITION

1. Test fuel pump circuit voltage, starting at START voltage check.

C—ENGINE WILL NOT START1. Test fuel injection module circuit voltage.2. Test fuel pump circuit voltage.3. Test fuel injector circuit voltage.4. Test engine speed circuit voltage.5. Test starter sensing circuit voltage.

D—ENGINE STARTS BUT RUNS ROUGH1. Test air temperature sensor circuit voltage.2. Test coolant temperature sensor circuit voltage3. Test throttle sensor circuit voltage.4. Test engine speed circuit voltage.

9/26/96 7 - 39

ELECTRICAL SYSTEMS ELECTRICAL SYSTEM DIAGNOSIS

CRANKING CIRCUIT TEST POINTSTEST CONDITIONS UNLESS SPECIFIED OTHERWISE-Ignition switch start position-PTO switch off position-Transmission in neutral

TEST POINTS NORMAL IF NOT NORMAL

1. battery positive 11.8-13.2 volts test battery

2. ignition switch terminal B battery voltage check battery cable connection, starter tie point, fusible link, and red wire to switch

3. ignition switch terminal A battery voltage test ignition switch

4. PTO switch battery voltage test yel/red wire, 20 amp fuse, and yel/blk wire

5. PTO switch battery voltage test PTO switch

6. transmission neutral switch battery voltage test pur wire, check connections

7. transmission neutral switch battery voltage test transmission neutral switch

8. ignition switch terminal S1 battery voltage test pur wire and connections

9. ignition switch terminal S2 battery voltage test ignition switch

10. start relay terminal 86 battery voltage test pur wire and connection, start relay

11. start relay terminal 85 less the 0.2 volt test relay ground circuit

12. start relay terminal 30 battery voltage test fusible link, red wire, and connections

13. start relay terminal 87 battery voltage less the 12 volts-test start relay12 volts-test pur/white wire, starter solenoid and starter

7 - 40 9/26/96


M53356

9/26/96 7 - 41


MAGNETO IGNITION AND IGNITION SWITCH SYSTEM GROUND TEST POINTS - 240/245/260/265When diagnosing ignition system, separate the ignitioncircuit from the ignition switch ground circuit as de-scribed in test number 1.TEST CONDITIONS UNLESS SPECIFIED OTHER-WISE-Ignition switch on-PTO off-Transmission in neutral


1. separate connector, test for spark using D05351ST spark testercrank engine

spark at plug test spark plug, test armature coil,check armature air gap, test controlmodule, check flywheel magnets

2 to 3. battery ground to check blk wire ground

continuity check battery cable connection, starter tie point, fusible link, and red wire to switch

3 to 4. engine ground to ignition switch terminal G

continuity check blk wire

4 to 5. ignition switch terminal G to ignition switch terminal M (ignition switch off)

continuity check ignition switch

5 to 6. ignition switch terminal M to ignition relay terminal 87A

continuity check wht wire

6 to 7. ignition relay terminal 87A to ignition relay terminal 30 (ignition switch on, transmission in gear, operator off the seat, PTO on)

continuity test ignition relay

7 to 8. ignition relay terminal 30 (meter red lead) to ignition relay terminal 85 (meter black lead) (ignition switch on)

.01 (reverse bias diode test) replace diode

8 to 3. ignition relay terminal 85 to engine ground

continuity test ground circuit

7 - 42 9/26/96


M53357

9/26/96 7 - 43


IGNITION SAFE RUN SYSTEM TEST POINTS - 240/245/260/265TEST CONDITIONS UNLESS SPECIFIED OTHER-WISE-Ignition switch on


1. battery position battery voltage test battery

2. ignition switch terminal B battery voltage check red wire, fusible link


4. seat switch battery voltage check yel/red wire, fuse, yel/blk wire

5. seat switch (operator on seat, PTO on)

battery voltage test seat

6. ignition relay terminal 86 battery voltage check pnk wire, test ignition relay

7. ignition relay terminal 85 less than 0.2 volt test relay ground

8. PTO switch (operator off seat, PTO off, transmission in neutral)

battery voltage test yel/blk wire


10. transmission neutral switch battery voltage check pur wire

11. transmission neutral switch battery voltage check transmission neutral start switch

12. ignition relay terminal 86 battery voltage check pur, pur/blk wires and diode

13. ignition relay terminal 85 less than 0.2 volt test relay ground circuit

7 - 44 9/26/96


M52468

9/26/96 7 - 45


Conditions:• Park brake engaged• Transmission in neutral• PTO switch disengaged• Spark plugs good condition or replaced• Spark plug lead connected to D05351ST Spark

Tester• Key switch in start position• Meter negative (-) lead on batter negative (-)

terminal• Meter positive (+) lead on numbered test point

IGNITION SYSTEM TEST POINTS - 285/320When diagnosing an ignition problem, check both sparkplugs for spark. If one spark plug produces a goodspark, the supply circuit (test points 2-20) is good andthe component circuit (test points 21-25) should bechecked. If both spark plugs DO NOT produce a goodspark, check the supply circuit (test points 2-20) first.Remember that this ignition circuit is a battery ignitionsystem and must have battery voltage at the positive ig-nition coil terminal to produce a spark. Also rememberthat the left coil and pulser are separated from the rightcoil and pulser.The test results can be compared from right side to leftside.

Test Location Normal If Not Normal

1. Spark tester spark test indicates hot blue spark both plugs

spark must jump gap of 4 mm (0.16 in.)

no spark both plugs - check supply circuit (test points 2-20) - continue testing.

no spark one plug - check component circuit (test points 21-25).

yellow spark - check coil.

Conditions:•Key switch in run position

Supply Circuit Tests:

2. battery positive terminal 11.8-13.2 volts test battery

3. ignition coil positive terminal and ignition module org/wht

battery voltage (maximum voltage drop 0.7 V)

no voltage - check supply circuit testpoints (4-20)

voltage - check component circuittest points (21-25)

low voltage - check for corrodedconnections in supply circuit testpoints (4-20)

4. key switch terminal B battery voltage check battery cable connection, fusible link, and red wires

5. key switch terminal A battery voltage test key switch

6. 20 amp fuse battery voltage test yel/red wire

7. 20 amp fuse battery voltage check 20 amp fuse

7 - 46 9/26/96


IGNITION CIRCUIT TEST POINT - 285/320—CONTINUED


8. PTO switch battery voltage test yellow/black wires


10. brake switch battery voltage test purple wire

11. brake switch battery voltage test brake switch

12. key switch terminal S1 battery voltage test purple wire

13. ignition relay terminal 86 battery voltage test pur/blk wire and diode

14. ignition relay terminal 87 battery voltage test yel/blk wire

Conditions:• seat switch depressed or

jumper wire installed inconnector

15. seat switch battery voltage test yellow/black wire

16. seat switch battery voltage test seat switch

Conditions:• voltage test light connected

to battery positive terminal(check for ground)

• key switch in off position

17. ignition relay terminal 85 light on bright light on - check ignition relay terminal 30, go to step 18

light dim or off - test ground circuit and check resistance, steps 17A-17B. Maximum 0.5 ohms resistance.

17A. engine ground terminal light on check battery negative cable and engine ground connection

17B. PTO relay terminal 85 light on light on - check black wire between ignition and PTO relay

light off - check black wire between PTO relay and engine ground

9/26/96 7 - 47


IGNITION CIRCUIT TEST POINT - 285/320—CONTINUED


Conditions:• key switch in on position

18. ignition relay terminal 30 battery voltage test or replace ignition relay

19. PTO relay terminal 87 battery voltage check pink wire

20. engine connector at terminal with yel/wht wire

battery voltage check pink wire and connection

battery voltage - check yel/wht wires between engine connector and ignition coils and ignition module, check connections

Component Circuit Tests:Conditions:

• voltage test light connectedto battery negative terminal(checking for current pulses)

• key switch in start position

21. ignition coil negative terminal rapidly flashing light, not steady glow flashing light check ignition coil - step 24

light steady glow - check ignition coil ground circuit, steps 22-23

Conditions:• voltage test light connected

to battery positive terminal(checking for ground)

• key switch in off position

22. ignition coil negative terminal light on bright light on - check pulser circuit, step 23

light dim or off - check coil groundcircuit and check resistance, steps22A-22C. Maximum 0.5 ohms resis-tance.

22A. ignition module ground terminal

light on check engine ground connection

22B. ignition module light on check blk/wht wire and connector

22C. ignition module light on light off - check ignition module connector, then replace ignition module

light on - check blk/yel and wht ignition coil wires and connector

7 - 48 9/26/96


IGNITION CIRCUIT TEST POINTS - 285/320—CONTINUED

Conditions:• meter set at AC voltage• key switch in start position


23. pulser coil connector - ignition module side of connector, meter leads on wht/blu and pnk, then on grn/wht and yel

small amount of voltage between 0.1—0.9 VAC, right and left pulser

voltage about the same

no voltage - test connection resistance and test pulser coil

voltage - replace ignition module

24. ignition coil-resistance primary - 3.4—4.6 ohmssecondary - 10.4—15.5K ohmscore-infinite

replace ignition coil

25. ignition module - replace ignition module with known good module

spark produced replace ignition module

9/26/96 7 - 49


M44982

7 - 50 9/26/96


CHARGE SYSTEM TEST POINTSThe tests should be performed in the order shown to simplify diagnostics.


1. battery positive 11.8—13.2 volts test battery

2. engine connector (see unregulated voltage output test)

30 VAC (min)—240/24527 VAC (min)—260/26526 VAC (min)—285/320

test stator, check flywheel magnets

3. regulator/rectifier (see regulated output test)

11A @ 12.2—13.8 volts (min) 240/24513A @ 12.2—3.8 volts (min) 260/265 test regulator15A @ 12.2—18.8 volts (min) 285/320 test regulator

test regulator

TEST CONDITIONS UNLESS SPECIFIED OTHERWISE-Disconnect battery positive cable for following continuity tests-ignition switch on position

3 to 1. charging circuit continuity test red wire, fusible link, positivebattery cable

5 to 6. sensing circuit continuity test yel/blk wire, 20 amp fuse, igni-tion switch, and fusible link

TEST CONDITIONS UNLESS SPECIFIED OTHERWISE-Connect battery cables for the following voltage tests-Ignition switch on position

7. brn wire battery voltage test regulator/rectifier

8. discharge lamp battery voltage test brn wire

9. ignition switch terminal G less than 0.2 volts test discharge lamp, blk wire, andground circuit

9/26/96 7 - 51


M53360

7 - 52 9/26/96


PTO CIRCUIT TEST POINTSTEST CONDITIONS UNLESS SPECIFIED OTHERWISE-Ignition switch on position-PTO switch off position-Operator on the seat


1. battery positive battery voltage test battery

2. ignition switch terminal B battery voltage check battery cable, fusible link, and connectors

3. 20 amp fuse battery voltage test ignition switch, test 20 amp fuse

4. seat switch battery voltage test yel/blk wire

5. seat switch battery voltage test seat switch

6. ignition relay terminal 86 battery voltage test pnk wire

7. ignition relay terminal 85 less than 0.2 volt test ground circuit

8. ignition relay terminal 87 battery voltage test yel/blk wire

9. PTO switch terminal D battery voltage test yel/blk wire

10. PTO switch terminal C battery voltage test PTO switch

11. PTO relay terminal 86 battery voltage test diode, pur/wht wire

12. PTO relay terminal 85 less than 0.2 volt test relay ground circuit

(-Engage PTO switch)

13. ignition relay terminal 30 battery voltage test ignition relay

14. PTO relay terminal 30 battery voltage test PTO relay, PTO relay diode

15. PTO switch terminal B battery voltage test blu wire

16. PTO clutch battery voltage less than 12 volts - test blu wire, PTO switch 12 volts - test PTO clutch

17. PTO clutch less than 0.2 volt test PTO clutch ground circuit

9/26/96 7 - 53


M53361

7 - 54 9/26/96


LOW FUEL INDICATOR CIRCUIT TEST POINTS - 240/245

NOTE: The following test procedure is designed to testvoltage through the circuit. To accomplish thistest the fuel tank has to be low on fuel or emptyfor sensor to complete a ground path and lightthe bulb.

TEST CONDITIONS UNLESS SPECIFIED OTHER-WISE-Ignition switch run position-Fuel tank empty or low on fuel



2. ignition switch terminal B battery voltage test red wire, fusible link, battery connection


4. 10 amp fuse battery voltage check fuse, test yel/red wire

5. indicator bulb battery voltage test yel/red wire to bulb, check bulb

6. indicator bulb less than 0.2 volt check blk/wht wire

7. sensor switch less than 0.2 volt check sensor switch and switch ground circuit

(remove wires to fuel sensor for test points 8)

8. fuel sensor continuity test sender

9. sensor ground less than 0.2 volt test sender, test ground circuit

9/26/96 7 - 55


M53362

7 - 56 9/26/96


HEADLIGHT CIRCUIT TEST POINTS

TEST CONDITIONS UNLESS SPECIFIED OTHERWISE-Ignition switch on position-Headlight switch on position



2. ignition switch terminal B battery voltage test red wire, fusible link



5. 20 amp fuse battery voltage test 20 amp fuse, fuse holder

6. light switch battery voltage test yel/blk wire

7. light switch battery voltage test headlight switch

8. headlights battery voltage less than 12 volts - test yel/wht wires12 volts - test lamps

9. headlight ground less than 0.2 volt test ground circuit

9/26/96 7 - 57


M53363

7 - 58 9/26/96


LOW OIL PRESSURE INDICATOR LIGHT SYSTEM TEST POINTS - 260/265

TEST CONDITIONS UNLESS SPECIFIED OTHERWISEIgnition switch on position



2. ignition switch terminal B battery voltage test fusible link, red wires




6. hourmeter battery voltage test yel wire

7. indicator bulb battery voltage test yel wire

8. indicator bulb less than 0.2 volt test indicator bulb, tan wire, and oil pressure sender

9/26/96 7 - 59


M53364

7 - 60 9/26/96



TEST CONDITIONS UNLESS SPECIFIED OTHERWISE-Ignition switch run position-Fuel tank empty or low on fuel






5. 10 amp fuse battery voltage test fuse

6. hourmeter tie point battery voltage test yel wire

7. bulb holder battery voltage test yel wire

8. bulb holder less than 0.2 volt test bulb and holder, low fuel sensor, and engine ground

9/26/96 7 - 61


M53365

7 - 62 9/26/96


HOURMETER CIRCUIT TEST POINTS - 260/265TEST CONDITIONS UNLESS SPECIFIED OTHERWISE-Ignition switch run position



2. ignition switch terminal B battery voltage test red wires, fusible link


4. battery side of fuse battery voltage test yel/red wire

5. hourmeter side of fuse battery voltage test fuse, fuse holder

6. hourmeter battery voltage less than 12 volts - test yel wire12 volts - test hourmeter

7. hourmeter less than 0.2 volt check ground circuit

9/26/96 7 - 63


M53366

7 - 64 9/26/96


LOW OIL PRESSURE INDICATOR LIGHT CIRCUIT TEST POINTS - 285/320

TEST CONDITIONS UNLESS SPECIFIED OTHERWISE-Ignition switch in the run position



2. ignition switch terminal B battery voltage test fusible link, red wire


4. fuse battery voltage test red wire

5. fuse battery voltage test fuse and fuse holder

6. hourmeter battery voltage test yel/blk wire

7. coolant temperature bulb tie battery voltage test yel wire

8. oil pressure light battery voltage test yel wire, and bulb

9. oil pressure light less than 0.2 volt test ground circuit, tan wire, oil pres-sure sensor and engine ground

9/26/96 7 - 65


M53367

7 - 66 9/26/96


HOURMETER CIRCUIT TEST POINTS - 285/320

TEST CONDITIONS UNLESS SPECIFIED OTHERWISE-Ignition switch in run position






5. 10 amp fuse battery voltage test 10 amp fuse


7. hourmeter less than 0.2 volt test ground circuit, hourmeter

9/26/96 7 - 67


M53368

7 - 68 9/26/96



TEST CONDITIONS UNLESS SPECIFIED OTHERWISE-Ignition switch run position-Fuel tank low on fuel or empty








7. indicator bulb battery voltage test yel wire, and bulb

8. indicator bulb less than 0.2 volt test blk/wht wire

9. low fuel sensor less than 0.2 volt test low fuel sensor switch, groundlead

9/26/96 7 - 69


M53369

7 - 70 9/26/96


COOLANT TEMPERATURE INDICATOR CIRCUIT TEST POINTS - 285/320

TEST CONDITIONS UNLESS SPECIFIED OTHERWISE-To test the circuit, remove the wire at the coolant temperature switch.-Ground this wire, and turn the ignition switch to the run position.







6. hourmeter tie point battery voltage test yel wire

7. indicator bulb battery voltage test yel wire, bulb

8. indicator bulb less than 0.2 volt test org/wht wire, engine connector,coolant temperature switch and en-gine ground

9/26/96 7 - 71


M53370

7 - 72 9/26/96


COOLANT TEMPERATURE BULB CHECK CIRCUIT TEST POINTS - 285/320

TEST CONDITIONS UNLESS SPECIFIED OTHERWISE-Disconnect the starter solenoid wire (pur/wht) and isolate it from ground. (This will allow you to perform the testprocedure without cranking the engine.)-Ignition switch in the start position -PTO switch off position-Transmission in neutral







6. PTO switch terminal D battery voltage test yel/blk wire

7. PTO switch terminal C battery voltage test PTO switch

8. transmission neutral switch battery voltage test pur wire

9. transmission neutral switch battery voltage test transmission neutral switch

10. ignition switch terminal S1 battery voltage test pur wire

11. ignition switch terminal S2 battery voltage test ignition switch

12. start relay terminal 86 battery voltage test pur wire

13. coolant temperature bulb check relay terminal 86

battery voltage test pur/blk wire, coolant tempera-ture bulbcheck relay


less than 0.2 volt check ground circuit


16. 10 amp fuse battery voltage test 10 amp fuse

17. indicator bulb battery voltage test yel wire

18. indicator bulb less than 0.2 volt test org/wht wire


less than 0.2 volt test relay


less than 0.2 volt test ground circuit

9/26/96 7 - 73


M53371

7 - 74 9/26/96


FUEL SHUT-OFF SOLENOID TEST POINTS - 240/245/260/265







6. shut-off solenoid battery voltage less than 12 volts - test yel/blk wire12 volts - test solenoid

7. engine ground less than 0.2 volt test engine ground strap

9/26/96 7 - 75


M53372

7 - 76 9/26/96


FUEL INJECTION MODULE CIRCUIT VOLTAGE TESTTest conditions: (unless otherwise specified)

• transmission in neutral• PTO switch off• park brake engaged• key switch in on position• meter negative (-) lead on battery negative (-) terminal• meter positive (+) lead on numbered test point• measure voltage with all connectors connected

Test/Check Point Normal If Not Normal

1. Battery positive terminal 11.2—13.8 volts Test battery

2. Fuel injection module relay terminal 2

Battery voltage Test yellow/white wire and ignition circuit


Greater than 0—less than 0.2 v Greater than 0.2 volts - test relay ground circuit

0 volts - test fuel injection module relay

4. Fusible link Battery Voltage Check battery cable connection, fusible link, and red wire


Battery voltage Test red/yellow wire


Battery voltage Replace fuel injection module relay

7. Fuel injection module pin 7 Battery voltage Test red/blue wire

8. Fuel injection module pin 16 Greater than 0—less than 0.2 v Greater than 0.2 volts - test fuel injection module ground circuit

0 volts - replace fuel injection module

9/26/96 7 - 77


M45348

7 - 78 9/26/96


FUEL PUMP CIRCUIT VOLTAGE TESTThe fuel pump turns on and off depending on fuelneeds. As a result, the fuel pump operates and must betested under specific conditions. The fuel pump oper-ates only under the following conditions:

• for about 5 seconds after key switch is turned ON.• when the starter solenoid is energized (start signal).• when an engine speed signal is sent to the fuel

injection module.






Greater than 0—less than 0.2 v Greater than 0.2 volts - test relay ground circuit0 volts - test fuel injection module relay

4. Fusible link Battery voltage Check battery cable connection, fusible link, and red wire






8. Fuel injection module pin 16 Greater than 0—less than 0.2 v Greater than 0.2 volts - test fuel injection module ground circuit0 volts - replace fuel injection module

Test conditions:• Turn key switch OFF then ON for each test point and measure voltage within 5 seconds.

9. Fuel injection module pin 21 Battery voltage for 5 seconds Replace fuel injection module

10. Fuel pump relay terminal 2 Battery voltage for 5 seconds Test red/black wire

11. Fuel pump relay terminal 1 Greater than 0—less than 0.2 v Greater than 0.2 volts - test fuel pump relay ground circuit0 volts - test fuel pump relay

Follow the test conditions carefully as they will changeseveral times during the test procedure.Test conditions: (unless otherwise specified)

• transmission in neutral• PTO switch off• park brake engaged• key switch in on position• meter negative (-) lead on battery negative (-)

terminal• meter positive (+) lead on numbered test point• measure voltage with all connectors connected

9/26/96 7 - 79


FUEL PUMP CIRCUIT VOLTAGE TEST—CONTINUED


12. Fusible link Battery voltage Check battery cable connection, fusible link and red wire

13. Fuel pump relay terminal 3 Battery voltage Test red/white wire

14. Fuel pump relay terminal 5 Battery voltage for 5 seconds Replace fuel pump relay

15. Fuel pump Battery voltage for 5 seconds Test purple wire

16. Fuel pump Greater than 0—less than 0.2 v Greater than 0.2 volts - test fuel pump ground circuitvolts - replace fuel pump

Test conditions:• turn key switch ON and wait for fuel pump to stop• connect jumper wire to battery negative (-) terminal and briefly jump to blue/black wire at connector between

ignition coil and ignition module while measuring voltage

10. Fuel pump relay terminal 2 0.7—13.8 volts Test starter voltage sensing circuit and if OK replace fuel injection module

Test conditions:• disconnect and ground spark plug wires• turn key switch ON and wait for fuel pump to stop• turn key switch to START and hold while measuring voltage

10. Fuel pump relay terminal 2 Battery voltage Test fuel injection module blue/black wire and if OK replace fuel injection module

7 - 80 9/26/96


M45356

9/26/96 7 - 81


• meter negative (-) lead on battery negative (-) terminal

• meter positive (+) lead on numbered test point • measure voltage with all connectors connected

FUEL INJECTOR CIRCUIT VOLTAGE TESTTest conditions: (unless otherwise specified)

• transmission in neutral• PTO switch off• park brake engaged• key switch in on position















10. Fuel injector Battery voltage Check red/white wire

11. Fuel injector Battery voltage Test fuel injector

12. Fuel injection module pin 12 Battery voltage Test white/blue wire


Test conditions:• disconnect and ground spark plug wires• put test light on fuel injector connector at blue/black wire• turn key switch to START position and watch test light

11. Fuel injector Test light blinks Test starter voltage sensing circuit, and engine speed circuit; if OK replace fuel injection module

7 - 82 9/26/96


M45357

9/26/96 7 - 83


BATTERY VOLTAGE SENSING CIRCUIT VOLTAGE TESTTest conditions: (unless otherwise specified)















9. Fuel injection module pin 4 Battery voltage Test red/yellow wire


7 - 84 9/26/96


M45358

9/26/96 7 - 85


STARTER VOLTAGE SENSING CIRCUIT VOLTAGE TESTTest conditions: (unless otherwise specified)



1. Batter positive terminal 11.2—13.8 volts Test battery





4. Fusible link Battery voltage Check battery cable connection, fusible link, and red wine







Test conditions:• disconnect and ground spark plug wires• turn key switch to START and hold while measuring voltage

9. Starter solenoid engagement terminal

10—13.8 volts Test cranking circuit

10. Fuel injection module pin 19 10—13.8 volts Test blue/red wire

7 - 86 9/26/96


M45359

9/26/96 7 - 87


THROTTLE SENSOR CIRCUIT VOLTAGE TESTTest conditions: (unless otherwise specified)














8. Fuel injection module pin 16 Greater than 0—less than 0.2 v Greater than 0.2 volts - test fuel injection module ground circuit0 volts-replace fuel injection module

9. Fuel injection module pin 17 8 volts Replace fuel injection module

10. Throttle sensor 8 volts Test red wire

11. Throttle sensor Greater than 0—less than 0.2 v Greater than 0.2 volts - test throttle sensor ground circuit through fuel injection module pins 5 and 160 volts - test throttle sensor

Test conditions:• throttle plate fully closed• move throttle lever from slow idle to fast idle while measuring voltage

12. Fuel injection module pin 11 0.3—7.5 volts Test white wire, throttle sensor, and throttle sensor position

7 - 88 9/26/96


M45360

9/26/96 7 - 89


ENGINE SPEED CIRCUIT VOLTAGE TESTTest conditions: (unless otherwise specified)















9. Engine speed connector Battery voltage Test ignition system

10. Fuel injection module pin 8 Battery voltage Test blue/black wire

7 - 90 9/26/96


M45361

9/26/96 7 - 91


COOLANT TEMPERATURE SENSOR CIRCUIT VOLTAGE TESTTest conditions: (unless otherwise specified)















9. Fuel injection module pin 10 0.5—4.6 volts Greater than 4.6 volts - test yellow wire and coolant temperature sensor0 volts - replace fuel injection module

10. Coolant temperature sensor 0.5—4.6 volts Test yellow wire and coolant temperature sensor

11. Coolant temperature sensor Greater than 0—less than 0.2 v Greater than 0.2 volts - test coolant temperature sensor ground circuit through fuel injection module pins 5 and 160 volts - test coolant temperature sensor

7 - 92 9/26/96


M45362

9/26/96 7 - 93


AIR TEMPERATURE SENSOR CIRCUIT VOLTAGE TESTTest conditions: (unless otherwise specified)








4. Fusible link Battery voltage Check battery cable connection, fusible link, and red wine







9. Fuel injection module pin 6 1.8—4.6 volts Greater than 4.6 volts - test blue wire and air temperature sensor0 volts - replace fuel injection module

10. Air temperature sensor 1.8—4.6 volts Test blue wire and air temperature sensor

11. Air Temperature sensor Greater than 0—less than 0.2 v Greater than 0.2 volts - test coolant temperature sensor ground circuit through fuel injection module pins 5 and 160 volts - test air temperature sensor

7 - 94 9/26/96


M45363

9/26/96 7 - 95


COMMON CIRCUIT TESTS

SHORTED CIRCUITA shorted circuit may result in the wrong component op-eration (i.e. improper wire-to-wire contact). To test for ashorted or improperly wired circuit:

1. Turn component switch ON.2. Start at the controlling switch of the component that

should not be operating.3. Follow the circuit and disconnect wires at

connectors until component stops operating.4. Shorted or improper connections will be the last two

wires disconnected.

HIGH RESISTANCE OR OPEN CIRCUITHigh resistance or open circuits usually result in slow,dim or no component operation (i.e. poor, corroded, ordisconnected connections). Voltage at the componentwill be low when the component is in operation.

To test for high resistance and open circuits:

1. Check all terminals and grounds of the circuit for corrosion.

2. If terminals are not corroded or loose, the problem is in the component or wiring.

M85600

M85601

GROUND CIRCUITS

Grounded circuits usually result in no component oper-ation or a blown fuse.

BATTERY TEST1. Clean battery terminals and top of battery.2. Inspect battery terminals and case for breakage or

cracks.3. Check electrolyte level in each battery cell. Add

clean, soft water as needed. If water was added, charge battery for 20 minutes at 10 amps.

4. Check specific gravity of each cell with a hydrometer.

• All cells less than 1.175: charge battery at 10 amprate.

• All cells more than 1.225 with less than 50 pointvariation: load test battery.

• All cells less the 1.225 with less than 50 pointvariation: continue test.

• More than 50 point variation: replace battery.

5. Check battery voltage with voltmeter of JT05685 Battery Tester.

• Battery voltage less than 12.4 V: see CHARGEBATTERY in this section.

• Battery voltage more than 12.4 V: see LOAD TESTBATTERY in this section.

M85602

M48318

7 - 96 9/26/96


CHARGE BATTERY

NOTE: See BATTERY TEST in this section beforecharging battery.

1. Connect variable rate charger to battery.

NOTE: Maximum charge time at boost setting is 10minutes. Allow additional 5 minutes for each 10degrees below 70 degrees F.

2. Start charger at slow rate. Increase charge rate one setting at a time. Check charger ammeter after 1 minute at each setting. Maintain 10 amp charge rate. Use boost setting as necessary.

3. Check if battery is accepting a 10 amp charge after 10 minutes at boost setting.

• Battery will not accept 10 amp charge after 10minutes at boost setting: replace battery.

• Battery is accepting 10 amp charge after 10minutes at boost setting, and battery did not needwater: go to steps 6 and 7.

• Battery is accepting 10 amp charge after 10minutes at boosting setting, but battery did needwater or all cells were below 1.175: go to steps 4and 5.

4. Set charger at 15—25 amps.

IMPORTANT: Decrease charge rate if battery gasesor bubbles excessively or becomes too warm totouch.

5. Check specific gravity after 30 minutes (60 minutes for maintenance-free battery).

• More than 50 point variation between cells: replacebattery.

• Less than 50 point variation between cells: go tosteps 6 and 7.

NOTE: If battery was discharged at slow or unknownrate, charge at 10—15 amps for 6—12 hours.(Maintenance-free battery: 12—24 hours.) Ifbattery was discharged at fast rate, charge at20—25 amps for 2—4 hours. (Maintenance—free battery: 4—8 hours.)

6. Continue charging battery until specific gravity is 1.230—1.265 points.

7. Load test battery. (See this section.)

LOAD TEST BATTERY

Connect JT05685 Tester to battery. Follow instructionson back of meter for testing battery. Replace battery asneeded.

REGULATED VOLTAGE OUTPUT TEST

SPECIFICATIONSFC420V . . . . . . . . . . . . 11 amps (MIN) at 12.2—13.8VFC540V . . . . . . . . . . . .13 amps (MIN) at 12.2—13.8VFD590V . . . . . . . . . . . .15 amps (MIN) at 12.2—13.8V

TEST EQUIPMENT• JT05712 Current Gun• JT05685 Battery Tester

IMPORTANT: Perform this test quickly to preventdamage to battery tested. DO NOT apply fullload to battery for more than 5—10 seconds.

1. Put JT05712 Current Gun over positive battery cable. Set Current Gun for DC current.

M48318

M48317

9/26/96 7 - 97


2. Turn load knob (A) fully out (counterclockwise). Connect JT05685 Battery Tester to battery.

3. Run engine at full throttle.4. Turn load knob in until maximum voltage and

amperage output is obtained. If reading does not meet specifications, see UNREGULATED VOLTAGE OUTPUT TEST in this section.

UNREGULATED VOLTAGE OUTPUT TEST - 240/245/260/265

SPECIFICATIONSEngine speed . . . . . . . . . . . . . . . . . . . . . . . . Fast idleMinimum voltage FC420V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 VAC FC540V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 VAC

TEST EQUIPMENT• Voltmeter

1. Disconnect stator 2-pin connector.2. Set voltmeter to AC voltage.3. Start and run engine at fast idle.

4. Connect meter across terminals (A).5. If reading is less than specification, see STATOR

RESISTANCE AND FLYWHEEL MAGNET TEST in this section.

UNREGULATED VOLTAGE OUTPUT TEST - 285/320

SPECIFICATIONSEngine speed . . . . . . . . . . . . . . . . . . . . . . . . Fast IdleMinimum voltage . . . . . . . . . . . . . . . . . . . . . . 26 VAC

M48319

A


1. Disconnect regulator-rectifier.2. Set voltmeter to AC voltage.3. Start and run engine at fast idle.

4. Connect meter across terminals (A).5. If reading is less than specification, see STATOR

RESISTANCE AND FLYWHEEL MAGNET TEST in this section.

TEST STATOR RESISTANCE

SPECIFICATIONFC420V and FC540V

stator resistance . . . . . . . . . . . . . 0.24—0.4 ohmsFD590V stator resistance . . . . . . . 0.12—0.19 ohms

TEST EQUIPMENT• Ohmmeter

1. Disconnect stator connector.

M48320

M48319

A

FC420V AND FC540V

7 - 98 9/26/96


2. Measure resistance across stator terminals (A).3. Replace stator is resistance does not meet

specifications.

TEST STARTER SOLENOID1. Put transmission in neutral2. Engage park brake.3. Disconnect and ground spark plug lead.4. Disconnect purple wire from starter solenoid lead.

5. Connect jumper wire to positive battery terminal and briefly jump to terminal (A).

• Starter runs: solenoid is good, check circuit wiring.(See this section.)

• Started does not run: go to step 66. Connect jumper wire between terminals (B).• Starter runs: Replace solenoid• Starter does not run: Check battery cables then

replace starter.

M48352

FD590V

M48356

TEST STARTER AMP DRAW

AMPERAGE SPECIFICATIONS (MAX)FC420V . . . . . . . . . . . . . . . . . . . .60 amps at 500 rpmFC540V . . . . . . . . . . . . . . . . . . . .85 amps at 500 rpmFD590V . . . . . . . . . . . . . . . . . . . .72 amps at 500 rpm

TEST EQUIPMENT• JT05685 Battery Tester• Photo Tachometer

1. Test system ground connections and battery.2. Disconnect and ground spark plug lead.

IMPORTANT: Turn load knob (A) fullycounterclockwise before making any testconnections.

3. Connect JT06585 Battery Tester to battery.4. Crank engine and read voltage and engine rpm.5. Turn ignition key to OFF. Adjust load knob until

battery voltage reads the same as when cranking.6. Read amperage on meter.7. Turn load knob fully counterclockwise.• Amps out of specification, or in specification but

rpm is low: see TEST STARTED NO-LOAD RPMin this section.

M48318

9/26/96 7 - 99


TEST STARTER NO-LOAD AMPERAGE

SPECIFICATIONS (MAX)FC420V or FD590V . . . . . . . . . . 50 amps at 6000 rpmFC540V . . . . . . . . . . . . . . . . . . . 50 amps at 5000 rpm

TEST EQUIPMENT• JT05712 Current Gun• Photo Tachometer

IMPORTANT: Complete this test in 20 seconds orless to prevent starter damage.

NOTE: Check that battery is fully charged and ofproper size to ensure accuracy of test.

1. Connect jumper cables to battery.

2. Connect negative cable to starter body. Connect positive cable to terminal (A).

3. Use jumper wire to briefly connect terminals (A) and (B).

4. Measure starter amperage and rpm. If amperage is out of specification, check for binding or seizing bearings, sticking brushes, dirty or worn commutator.

TEST STARTER NO-LOAD RPM

SPECIFICATION (MIN)FC420V or FD590V . . . . . . . . . . . . . . . . . . . .6000 rpmFC540V . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5000 rpm

TEST EQUIPMENT• Photo Tachometer

M48355

IMPORTANT: Complete this test in 20 seconds orless to prevent starter damage.

NOTE: Check that battery is fully charged and ofproper size to ensure accuracy of test.

1. Connect jumper cables to battery.

2. Connect negative cable to starter body. Connect positive cable to terminal (A).

3. Use jumper wire to briefly connect terminals (A) and (B).

4. Measure starter rpm with photo tachometer. Replace or repair starter that does not meet specifications.

ADJUST IGNITION COIL AIR GAP -FC420V AND FC540V

SPECIFICATIONIgnition coil air gap . . . . . . . . . . . 0.3 mm (0.012 in.)

TEST EQUIPMENT• Feeler Gauge

1. Turn flywheel magnet away from coil.

M48357

M48358

7 - 100 9/26/96


2. Loosen coil mounting screws (A).3. Insert a feeler gauge between flywheel and coil

legs. Align flywheel magnet with coil. Adjust gap to 0.3 mm (0.012 in.).

4. Tighten coil mounting screws. Turn flywheel to remove feeler gauge.

TEST IGNITION COIL - FC420V AND FC540V

SPECIFICATIONSPrimary lead and core

resistance . . . . . . . . . . . . . . . . . . 0.48—0.72 ohmsSpark plug lead and core

resistance . . . . . . . . . . . . . . . . .10.9—16.3 K ohm


1. Remove spark plug cap from spark plug wire.

2. Measure resistance between primary lead (A) and core (B), and between spark plug lead (C) and core (B).

3. Replace coil that does not meet specifications.

IGNITION MODULE TESTREASON:To determine if ignition module is defective.

NOTE: The following procedure is a functional test ofthe ignition components. Components must betested by function.

M48360

A

C

B

PROCEDURE:1. With the key on:a. Measure DC voltage across top of battery posts.b. Measure DC voltage between engine block (not

frame or battery) and positive terminal of both the left and right coils.

c. If voltage is the same, go to step 2.d. If voltage is more than 0.7 volts lower at the coils

than battery, check the following:• Battery terminal connection.• Battery to engine ground.• Positive side circuit from coil to battery.

2. With engine cranking, measure AC voltage across pulsar leads (pulsar side of connector). Left pulsar has pink with white/blue wires, right pulsar has yellow with green/white wires.

a. Pulsars should each produce low levels of AC voltage (as low as 0.05 VAC).

b. If no output, replace pulsars.c. If output OK, go to step 3.

3. With engine cranking, use test light to check for pulsation at negative terminal of both the left and right coils.

a. Pulsation indicates ignition module and pulsars are functioning properly. Problem is with ignition coil, spark plug, or spark plug cap.

b. If no pulsation and pulsar output OK, check the following:

• Resistance at connector for coils negative lead and pulsar connectors.

• Ignition module ground (black/white) wire connection to engine.

4. If battery voltage is at coil, pulsars are OK, connections test good, and proper ground is positively verified, replace ignition module.

PULSER COIL TEST - FD590V

SPECIFICATIONSPulser coil resistance . . . . . . . . . . . . 85—270 ohmsPulser coil voltage . . . . . . . . . . . . . . . . . . 0.05—0.9 V

TEST EQUIPMENT• Ohmmeter• Voltmeter

1. Turn key switch off.2. Disconnect 4-pin pulser connector.

9/26/96 7 - 101


3. Measure resistance between white/blue wire (A) and pink wire (B), then green/white wire (C) and yellow wire (D) at pulser side of connector.

4. Connect 4-pin pulser connector.5. Set voltmeter for AC voltage.6. Connect meter across white/blue (A) and pink (B)

wires at ignition module side of connector.7. Crank engine and read voltage.8. Connect meter across green/white (C) and yellow

(D) wires. Crank engine and read voltage.9. Compare voltage between steps 6 and 8. They

should be close to the same. Some voltage indicates the pulser coils are good.

10. If resistance or voltage does not meet the specifications, replace pulser.

IGNITION COIL TESTS - FD590V

SPECIFICATIONSPrimary coil resistance . . . . . . . . . . . 3.4—4.6 ohmsSecondary coil resistance. . . . . 10.4—15.5 K-ohmsCore insulation continuity. . . . . . Infinite resistance


1. Turn key switch off.2. Disconnect wires from coil.3. Disconnect spark plug wires from spark plugs.

Remove spark plug cap from spark plug wire.

M48361

4. Measure resistance of primary coil across terminals (A and B).

5. Measure secondary resistance between coil positive terminal (A) and spark plug wire (C).

6. Check for core insulation continuity between negative terminal (B) and core (D) and spark plug wire (C) and core. There should be no continuity (infinite resistance.)

7. If resistance does not meet specifications, replace coil.

SPARK PLUG CAP TESTSPECIFICATIONSpark plug cap resistance. . . . . . . . .marked on cap


1. Turn key switch off.2. Disconnect spark plug cap.

3. Measure resistance across spark plug cap terminals. Resistance should be about the same as marked on the spark plug cap.

4. If resistance does not meet specification, replace spark plug cap.

M48362

M48364

7 - 102 9/26/96


SPARK TESTREASON:Check overall condition of ignition system.

EQUIPMENT:• D-05351ST Spark Tester

CONNECTIONS:1. Park brake engaged. PTO disengaged.

2. Remove high tension lead (A) from spark plug.3. Connect spark tester (B) to spark plug.4. Connect high tension lead to spark tester.5. Adjust spark tester gap to 4.2 mm (0.166 in.) (4

turns) with screw (C).

NOTE: DO NOT adjust spark tester gap beyond 5.0mm (0.200 in.) (5 turns) as damage to ignitionsystem components could occur.

6. Set key switch to run position.

M49887

FC420V and FC540V

A B

DC

M49895

FD590V

A

DB

C

PROCEDURE:1. Spin engine with starter and watch spark (D) at

spark tester. If engine will start, watch spark with engine running.

SPECIFICATIONS• Steady, strong, blue spark.

RESULTS:• If spark is weak, or if no spark, install a new spark

plug and test again.• If spark is still weak, or still no spark, run tests on

individual components to find cause ofmalfunction.

ADJUST SPARK PLUG GAPSPECIFICATIONSpark plug gap:

FC420V and FC540V . . . . . . . . . . . . . 0.7—0.8 mm(0.028—0.032 in.)

FD590V . . . . . . . . . 0.6—0.7 mm (0.024—0.028 in.)EFI . . . . . . . . . . . . . . . 1.0—1.1 mm (0.40—0.44 in.)

Spark plug torque:FC420V and FC540V . . . . . . . . 20 N·m (177 lb-in.)FD540V . . . . . . . . . . . . . . . . . . . 17 N·m (150 lb-in.)

IMPORTANT: DO NOT clean spark plug with sandpaper or abrasives. Engine scoring can result.

1. Scrap or wire brush deposits from spark plug.2. Inspect spark plug for:• Cracked porcelain• Pitted or damaged electrodes.

3. Check spark plug gap (A) using a wire feeler gauge. Set gap to specifications.

4. Install and tighten spark plug to specification.

M85608

9/26/96 7 - 103


TEST KEY SWITCH1. Disconnect key switch connector.2. Check terminals for continuity using an ohmmeter

or continuity tester.

KEY SWITCH CONTINUITY SPECIFICATIONSKey Switch Position Terminal ContinuityOff . . . . . . . . . . . . . . . . . . . . . . . . . . . M—G (A and B)Run . . . . . . . . . . . . . . . . . . . . . . . . . . .B—A (C and D)Start . . . . . . . . . . . . . . . . . . . . . . . . . . B—A (C and D),

S1—S2 (E and F)

3. Replace key switch if continuity is not correct.

TEST FLYWHEEL MAGNET

1. Hold a steel tool about 25 mm (1 in.) from flywheel magnet. The tool should be attracted by the magnet.

2. Replace flywheel if magnet is weak.

M48366

M48367

TEST FUEL SHUT-OFF SOLENOID - FC420V AND FC540V

1. Disconnect fuel shut—off solenoid connector.

2. Remove fuel shut-off solenoid.

3. Connect jumper wire to solenoid terminal (A).4. Ground solenoid.5. Connect jumper wire to positive battery terminal.

NOTE: It may be necessary to push plunger slightly forplunger to retract.

6. Solenoid plunger (B) must retract. Solenoid must extend when the jumper wire is removed.

7. If the solenoid plunger does not move, replace solenoid.

c CAUTIONGasoline will drain from carburetor whensolenoid is removed. Keep gasoline away fromsparks, flame, or hot engine parts or personalinjury can result.

M48368

7 - 104 9/26/96


TEST LOW FUEL SWITCH

1. Disconnect low fuel switch connector. Remove low fuel switch.

2. Check continuity across terminals (A).3. Slide float (B) on shaft.4. Switch should have continuity only when float is at

bottom of shaft.5. If continuity is not correct or float contains fuel,

replace low fuel switch.

TEST TRANSMISSION NEUTRAL SWITCH - HYDROSTATIC TRANSMISSION

1. Disconnect transmission neutral switch connector.

2. Check continuity across terminals (A).3. Switch should have continuity only when the

plunger is depressed (brake pedal depressed).4. If the continuity is not correct, replace switch. If the

switch has continuity when the plunger is depressed, but not when the brake pedal is depressed, adjust the switch position.

M48369

M48370

ADJUST TRANSMISSION NEUTRAL SWITCH - HYDROSTATIC TRANSMISSION

1. Lock master brake on.

2. Loosen nuts (A).3. Adjust brake switch so plunger is depressed by

bracket (B).4. Tighten nuts.

TEST TRANSMISSION NEUTRAL SWITCH - GEAR TRANSMISSION

1. Disconnect transmission neutral switch connector.

2. Check continuity across terminals (A).3. Switch should have continuity only when the

transmission lever is in neutral.4. If the continuity is not correct, replace switch.

M48371

M48372

9/26/96 7 - 105


TEST PTO SWITCH1. Disconnect PTO switch connectors.

2. Turn PTO switch off. There should be continuity only between terminals (B and E) and (C and D).

3. Turn PTO switch on. There should be continuity only between terminals (B) and (A).

4. Replace PTO switch if continuity is not correct.

TEST PTO CLUTCHSPECIFICATIONSPTO clutch current draw (min.). . . . . . . . . . . 4 amps

TEST EQUIPMENT• Ohmmeter• JT05712 Current Gun

1. Put current gun over blue PTO clutch wire (B).2. Install a jumper wire in seat switch connector to

bypass seat switch.3. Turn key switch and PTO switch on.4. Measure PTO clutch current draw. Normal current

draw is about 4 amps. Low current draw will cause a weak PTO clutch.

5. If current draw is low, replace PTO clutch.

M48373

M48375

TEST RELAY1. Disconnect relay connector.2. Check terminal continuity using an ohmmeter or

continuity tester.

3. There should be continuity between relay terminals 87A-30 (A and B) and 85-86 (C and D). There should be no continuity between relay terminals 87 and 30 (E and B).

4. Connect a jumper wire from battery positive terminal to relay terminal 85. Connect a jumper wire from relay terminal 86 to ground.

5. There should be continuity between relay terminals 87 and 30.

6. If continuity is not correct, replace relay.

ADJUST ELECTRIC PTO CLUTCH

PTO CLUTCH AIR GAP SPECIFICATIONSWarner . . . . . . . . . . 0.38—0.64 mm (0.015—0.025 in.)Ogura. . . . . . . . . . . 0.30—0.51 mm (0.012—0.020 in.)

SHOP EQUIPMENTWarner clutch . . . . 0.51 mm (0.020 in.) feeler gaugeOgura clutch . . . . 0.41 mm (0.016 in.) feeler gauge

1. Make sure key switch and PTO switch are in OFF position. Remove key.

2. Insert feeler gauge through slot in brake plate. Gauge should be between clutch rotor and armature.

M48376

7 - 106 9/26/96


3. Tighten lock nut (A) until feeler gauge begins to bind between armature and rotor. Use a sweeping motion with feeler gauge while making this adjustment. DO NOT overtighten.

4. Repeat procedure on other two adjusting nuts.5. Engage and disengage clutch several times.

Recheck adjustment.

TEST HEADLIGHT SWITCH1. Disconnect headlight switch connector.

2. Check continuity across switch terminals (A). Terminals should have continuity only when switch is ON.

3. If continuity is not correct, replace headlight switch.

TEST SEAT SWITCH1. Turn key switch off.2. Disconnect seat switch connector.

M48377

M48378

3. Check continuity across switch terminals (A). There should be continuity only when plunger is depressed.

4. If continuity is not correct, replace seat switch.

THROTTLE SENSOR TEST

SPECIFICATIONInput terminal resistance. . . . . . . . .3.3—6.8 K ohmsOutput terminal resistance (idle) . .0.2—0.5 K ohms


1. Be sure key switch is in OFF position.2. Disconnect throttle sensor connector.3. Move throttle lever to show idle position.

4. Connect ohmmeter negative lead to ground terminal (A). Connect ohmmeter positive lead to input terminal (B). Measure resistance across the input terminal. Move the throttle lever slowly to fast idle and watch resistance reading. Resistance reading must decrease as throttle lever moves toward fast idle position.

M48379

M48380

9/26/96 7 - 107


5. Move throttle lever to slow idle position.6. Connect ohmmeter positive lead to output terminal

(C). Ohmmeter negative lead connected to ground. Measure resistance across the output terminal.

7. If resistance does not meet specifications, replace throttle sensor.

THROTTLE SENSOR ADJUSTMENT - 285 FUEL INJECTED

SPECIFICATIONThrottle sensor

output voltage . . . . . . . . . . . . . . . 0.35—0.38 volts


1. Move throttle lever to slow idle position.

2. Turn slow idle stop screw (A) counterclockwise several turns to be sure the throttle plate in the throttle body is fully closed.

3. Loosen the throttle sensor cap screws.

4. Connect voltmeter negative lead to battery negative terminal. Connect meter positive lead to throttle sensor connector white wire (B).

M48381

M48382

5. Turn key switch to ON position.6. Turn throttle sensor until the voltage is between

0.35—0.38 volts. Hold throttle sensor in position and tighten cap screws.

7. Open and close the throttle plate several times and check voltage again. Readjust if necessary.

8. Adjust slow idle stop screw.

AIR TEMPERATURE SENSOR TEST - 285 FUEL INJECTED

AIR TEMPERATURE SENSOR SPECIFICATIONResistance at 20°C (68°F) . . . . . . . .1.9—3.1 K ohmsResistance at 0—30°C (32—86°F). .7.4—1.3 K ohms


1. Turn key switch off.2. Disconnect air temperature sensor connector.

3. Measure resistance across air temperature sensor terminals (A).

4. If resistance does not meet specifications, replace the air temperature sensor.

COOLANT TEMPERATURE SENSOR TEST - 285 FUEL INJECTED

COOLANT TEMPERATURE SENSOR SPECIFICATIONResistance at 20°C (68°F) . . . . . . . .1.9—3.1 K ohmsResistance at 0—30°C (32—86°F). .7.4—1.3 K ohms


M48383

7 - 108 9/26/96


1. Turn key switch off.2. Disconnect coolant temperature sensor connector.

3. Measure resistance across coolant temperature sensor terminals (A).

4. If resistance does not meet specifications, replace the coolant temperature sensor.

TEST FUEL PUMP OR FUEL INJECTION MODULE RELAY - 285 FUEL INJECTED

1. Disconnect relay connector.2. Check terminal continuity using an ohmmeter or

continuity tester.

3. There should be continuity between relay terminals 1 and 2. There should be no continuity between relay terminals 3 and 5.

4. Connect a jumper wire from battery positive terminal to relay terminal 1. Connect a jumper wire from relay terminal 2 to ground.

5. There should be continuity between relay terminals 3 and 5.

6. If continuity is not correct, replace relay.

M48384

M48385

FUEL INJECTOR TEST - 285 FUEL INJECTEDFUEL INJECTOR SPECIFICATIONResistance at 20°C (68°F) . . . . . . . 11.1—12.9 ohms


1. Turn key switch off.2. Disconnect fuel injector connector.

3. Measure resistance across fuel injector terminals (A).

4. If resistance does not meet specifications, replace the fuel injector.

5. Connect a jumper wire from battery negative terminals to fuel injector terminal. Briefly and repeatedly connect a jumper wire from battery positive terminal to the other fuel injector terminal. The fuel injector must click each time the jumper wire contacts the terminal.

6. If the fuel injector does not click, replace the fuel injector.

TEST DIODE

1. Connect diode tester, ohmmeter, or continuity tester to each lead of diode. Check for continuity.

M48386

M48387

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2. Reverse leads. Check for continuity.3. Diode should have continuity in one direction only.

Replace defective diode.

M48388

TEST GROUND CIRCUIT

1. Connect ohmmeter or continuity tester to negative terminal of battery and ground terminal of circuit or component to be tested.

2. Check for continuity. If continuity is not indicated, check for open wiring or poor connections.

M48389

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ELECTRICAL SYSTEM SCHEMATICS ELECTRICAL SYSTEMS

M79563

ELECTRICAL SYSTEM SCHEMATICS

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ELECTRICAL SYSTEMS ELECTRICAL SYSTEM SCHEMATICS

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TICS

- 111


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ATICS

- 113


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ATICS

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