aes pr

AUTOMOBILE ENGG. 5TH

SEM AES LAB MANUAL ER. GURPARTAP SINGH BRAR

PRACTICAL No. 1.

AIM: - To understand the layout of complete wiring system of an automobile.

DIAGRAM: -



PRACTICAL No. 1.

AIM: - To understand the layout of complete wiring system of an automobile.

THEORY: -

The colour coding for electrical system provides a means of circuit tracing for the automobile

electrician. The majority of motor vehicles conform to the colour coding standard and the knowledge of

this is invaluable when used in conjunction with the wiring diagram. The colour coding may vary from

model to model. But the colour coding adopted for a particular model is clearly given on the makers

wiring diagram.

Main Feed Colour

There are seven main feed colours, each of which is allocated to a particular circuit. Feed wires are

braided in the main circuit colour, switch wires are braided in the main colour but carry also a coloured

tracer woven spirally into the braiding, return or ground leads are black.

1. Brown: - Battery circuit interior light, horn, control box, ammeter, ignition switch.

2. Yellow: - Generator circuit-generator terminals to control box terminals and to ignition warning

light.

3. White: - Ignition circuit-all units which are wired through the ignition switch and which are

essential for the starting and running of the vehicle and which are not fused, i.e., electric control

pump, startin motor, solenoid switch, etc.

4. Green: - Fused auxiliary circuits which are fed through the ignition switch, i.e., stop lamps, fuse

gauge, direction indicators, windshield wiper, etc.

5. Light Green: - Flasher unit to flasher indicator waving light.

6. Blue: - Head lamp circuit fed from terminals on lightning switch.

7. Red: - Side and tail lamp circuits fed from lightning switch. Included in this circuit are fog

lamps, panel lights, door lights, etc., which are only required when the side lamps are switched

on.

8. Black: - All ground wired. If a unit do not internally grounded, or is mounted on an insulated

portion of the vehicle, a cable must be connected from the body of the unit to a good ground

point on the chassis.



PRACTICAL No. 2.

AIM: - Testing of battery with hydrometer, high rate of discharge tester, charging of batteries.

APPARATUS: - Battery, gloves, hydrometer, voltmeter, goggles.

DIAGRAM: -



PRACTICAL No. 2.

AIM: - Testing of battery with hydrometer, high rate of discharge tester, charging of batteries.

APPARATUS: - Battery, gloves, hydrometer, voltmeter, goggles.

THEORY: -

Battery: - It is a device which is used to store the current in the form of chemical energy. The various

types of batteries are: -

1. Lead-Acid battery

2. Dry charged battery

3. Alkaline battery

The battery is an electrochemical device. It uses chemical to produce electricity. The amount of

electricity it can produce is limited. As the chemical in the battery is depleted, the battery runs down

and is discharged. It can be recharged by supplying it with electric current from the vehicle alternator or

from a battery charger. The depleted chemicals are restored to their original condition as the battery

becomes charged.

The automotive battery supplies electric current to operate the starting motor and ignition system while

starting the engine. It also acts as a voltage stabilizer by supplying current for the lights, radio and other

electrical accessories when the alternator is not handling the load. In addition, the battery supplies a

small amount of current to the volatile memory in the electronic control module while the ignition key

is off. The specific gravity test and the open voltage test are conducted to find out the state of charge in

the battery. Load test is performed to find out the battery condition.

Specific Gravity: - It is defined as the weight of the any material or an electrolyte in case of battery

compared with the same volume of chemically pure water.

Battery Capacity: - It is defined as the maximum amount of the current that a battery can deliver based

on the area of the plate surface in contact with the electrolyte as well as number of plates and amount as

well as quantity.

PROCEDURE: -

BATTERY VISUAL INSPECTION: A cranked cover on a top terminal battery may result from using

the wrong wrench to turn the nut on the cable clamp bolt. Over tightening the hold down clamps may

crack the case. Over tightening the cable bolts in side-terminal batteries may pull the terminal loose.

On vent-cap batteries, remove the vent caps check the electrolyte level. Add water if needed.

CLEANING THE BATTERY: Top-terminal batteries may corrode around the terminals and clamps.

Disconnect the cables and clean the terminals and clamps with a battery-terminal brush. Brush the

battery top with a solution of baking soda with water. After the foaming stops, flush off the battery and

top with water. To retard corrosion, coat the terminals with anticorrosion compound.



OBSERVATION TABLE: -

State of charge Specific Gravity Freezing Point

Fully Charged 1.260 to 1.280 -700 F to - 92

0 F

Half Charged 1.205 to 1.260 - 170 F to - 60

0 F

Battery Needs Charging 1.180 to 1.220 -060 F to - 31

0 F

Full Discharged 1.100 to 1.130 +190 F to + 10

0 F

Open circuit voltage test:

Sr. No. Voltage Condition of battery

Load test:

Sr. No. Voltage (v) Condition

Good Weak Bad



(A)Open circuit voltage test

1. Open circuit voltage of the battery is measured with the help of an ordinary voltmeter.

2. Connect the terminals of the battery across a voltmeter and find out the voltage supplied by the

battery.

3. The voltmeter reading represents the battery state of charge. If the voltage is below 12.40 volts,

charge the battery.

(B) Testing of battery with hydrometer

1. Battery is to be taken/selected for the test.

2. Take hydrometer, the end of hydrometer is inserted into one of the cells and rubber bulb is

operated.

3. Now the graduated float takes up a particular position level with the scale level reading of the

electrolyte provide its specific gravity due to comparison of the acid solution with that of the

pure water.

4. By means of rubber bulb at one end of the syringe and the other end a sample of electrolyte is

withdrawn from the cell into the glass body of the syringe.

5. The float will assume a certain position based upon the strength of the electrolyte or state of

charge of battery.

6. The reading on the scale on the float will indicate specific gravity of battery.

(C) Battery load test

1. After a battery passes charge test, it is tested for load test.

2. This test measures the terminal voltage of battery while it is discharging at a high rate.

3. The test is performed with a load tester that includes a voltmeter, ammeter and loading device.

4. Apply 15 A load for 15 seconds. This is done to remove any surface charge present in battery.

5. Then apply a load equal to half the CCA and note the voltage and condition of the battery.

6. If the voltage is below 9.6 volt, recharge the battery and retest it. A battery that fails the load

test a second time is defective.

(D) High discharge test

1. Put heavy/high discharge on the battery.

2. Now measure the battery voltage.

3. If voltage is low when the load is applied on it, it means battery is either discharge or worn out.

(E) Charging of battery

1. For charging of battery its positive and negative terminals should be connected to the respective

terminals of the battery charger.

2. The current should be adjusted as per battery specifications.

3. Recharge the battery till gassing starts.

4. Now decrease the charging current.



5. Again charge battery till specific gravity does not increase.

6. Take readings of specific gravity after certain time.

RESULT:

Thus the specific gravity test, open voltage test and a load test were conducted and the state of charge

was found for the given battery.

1. The state of charge as found by specific gravity test is ---------------------.

2. The state of charge as found by open voltage test is ------------------------.

3. Battery voltage from load test --------------------.

4. The condition of the battery found from load test --------------------.

PRECAUTIONS: -

1. Use gloves and goggles while performing this job.

2. Hydrometer reading should not be taken when the cell has been recently topped up with

distilled water.

3. The reading should be taken after a run or after mixing the electrolyte thoroughly.

4. The temperature of the electrolyte during charging process should not be allowed to exceed

beyond 45oC.



PRACTICAL NO. : - 4

AIM: - To conduct performance test on a dynamo, alternator & starter motor.

APPARATUS REQUIRED: Test Bench, Voltage Tester, Alternator, Digital Tachometer, Battery,

Starter Motor



PRACTICAL NO. : - 4.

AIM: - To conduct performance test on a dynamo, alternator & starter motor.

APPARATUS REQUIRED: Test Bench, Voltage Tester, Alternator, Digital Tachometer, Battery,

Starter Motor

THEORY:

ALTERNATOR: The alternator converts mechanical energy from the engine into electrical energy. It

is usually mounted on the side of the engine. The engine crankshaft pulley drives the alternator through

a belt at two or three times the crankshaft speed. A regulator in the alternator prevents the alternator

from producing excessive voltage. Some manufacturers call the alternator a generator or a.c generator.

The alternator restores the charge to the battery and also handles the load of the ignition, lights, radio

and other electrical and electronic equipments while the engine is running. The speed of the generator

at which its output voltage just rises above voltage of the battery being charged is called cutting- in

speed.

TESTS CONDUCTED ON ALTERNATOR:

1. Alternator performance characteristics.

2. Alternator output test.

3. Cut-in and cut-out voltage of alternator.

PROCEDURE:

1. The alternator is mounted on the test bench and the connections are made. Alternator is

connected to battery and to the test bench.

2. The drive to the alternator is given by means of a variable speed electric motor.

3. With proper connections and the alternator is not running, the charging indicator in the test

bench remains on. This indicates that the battery is not charging.

4. Start the electric motor and allow the alternator to rotate at slow speed. The alternator speed is

measured by means of a tachometer. When the alternator rotates at low speed, the output

voltage value is zero and the charge indicator lamp remains on.

5. Gradually increase the speed of alternator. With increase in speed, the output voltage increases.

At a particular speed, the voltage reaches a steady value and the charge indicator lamp goes off.

This is the cut-in speed of the alternator. Note down the alternator speed and voltage. Also note

the current value at that condition.

6. To conduct the performance test, the alternator is brought to zero speed. Gradually increase the

alternator speed from zero RPM to the rated speed by varying the motor speed. For each speed,

note down the current and voltage output produced by the alternator. Plot a graph with speed

along X-axis and voltage & current along Y-axis and check whether it matches with

manufacturers specification.

7. To find out the cut-off speed of the alternator, the alternator speed is reduced gradually from the

rated speed and at a particular speed, the charge indicator light gets on is known as the cut-off

speed of alternator. Note down the voltage and current at that stage. The voltage indicates the

cut-off voltage of alternator.



8. To conduct the alternator output test, the alternator is made to run at the rated speed and the

load is applied to the alternator. By applying the load and maintaining the alternator speed

constant, check whether it produces the rated current and voltage as specified by the

manufacturer.

STARTER MOTOR:

To start the engine, the crankshaft must turn fast enough for air-fuel mixture to enter the cylinder. An

electric starter or starting motor does the job. It converts electrical energy from the battery into

mechanical energy that rotates the crankshaft. When the driver turns the ignition key to start, the

control circuit causes contacts to close in a starter relay or solenoid switch. High current then flows

from the battery to the starter motor. As the starter motor shaft turns, it turns the crankshaft fast enough

to start the engine.

TESTS CONDUCTED ON STARTER MOTOR:

1. No load test.

2. Current draw test.

PROCEDURE:

NO LOAD TEST:

1. Starter motor is firmly mounted on the test bench. Better supply is connected to the starter

motor and ammeter and voltmeter are connected across the battery to measure the current and

voltage drawn by motor.

2. Turn on the ignition key and find out the voltage and current drawn by the battery. Also note

down the motor speed. Check whether the reading obtained are as per the manufacturers

specification. If not, find out and rectify the fault.

CURRENT DRAW TEST:

1. This test measures the current flow to the starter motor while it cranks the engine.

2. Disable the ignition coil and connect ammeter to the battery cable.

3. Turn ignition key to start and read the current draw and note down it. Check whether it is

according to manufacturer specification. If not, find and rectify the fault

RESULT:

Thus the given alternator and starter motor are tested and the results are tabulated.



PRACTICAL NO. : - 6

AIM: - Understand and test the conventional ignition system, setting of contact breaker points and

spark plug gap.

APPARATUS: - Battery 6 or 12 volts, ignition coil, ignition distributor, contact breaker, feeler gauge,

spark plug etc.

DAIGRAM:-

Contact Breaker Point

Spark Plug Gap Checking



PRACTICAL NO. : - 6

AIM: - Understand and test the conventional ignition system, setting of contact breaker points and

spark plug gap.

APPARATUS: - Battery 6 or 12 volts, ignition coil, ignition distributor, contact breaker, feeler gauge,

spark plug etc.

THEORY:-

Introduction: - When a current of high ignition tension and high voltage is passed across the air gap

then it produces a spark there. When this spark is produced at the spark plug to ignite the air fuel

mixture in the combustion chamber then it is called ignition system. The ignition systems are classified

as (a) battery ignition system (b) magnet ignition system.

Battery ignition system: - The system consists of two circuit, the primary and secondary circuits. In

primary circuit a battery of 6 to 12 volts, ammeter, and ignition switch, primary winding of ignition

coil, contacts breaker and condenser. The secondary circuit contains secondary winding of ignition coil,

distributor and the sparking plug.

When the contact breaker point is in closed position then the current passes through the primary

circuits develops magnetic field in the ignition coil. As soon as the contact breaker points are opened by

means of cam system the magnetic field developed in the ignition coil is collapsed suddenly, by which

a high voltage source is produced in secondary winding .this high voltage is led to each spark plug in

turn by means of distributor thus produces a spark at the electrodes of the plug. As per setting of

ignition timing. Thereby ignition the compressed charge inside the cylinder.

Spark plug: - An element which is conduct the high potential from the ignition harness into the

combustion chamber is called spark plug. It is provided with a gap across which the high potential

discharges thereby producing a spark and burning the charge in combustion chamber.

The requirements of a good spark plug are given:-

1. It must have a high resistance so that current may be leaked thus produce spark.

2. It must maintain proper air gap between the two electrodes under all conduction.

3. It must be gas tight because leakage may cause the high temperature which results disintegration

between the insulator and electrode.

4. It must have high resistance correction thereby maintaining a proper gape length at high sparking

potential.

5. It must have sufficient reach length. As the long reach plug reduces and the short reach plug

increase combustion space.

6. Spark plug gap: - The factors, as the type of fuel mixture ratio and compression ratio effect the electrical resistance of spark plug. Therefore to obtain best sparking results and adjustment of air

gap between two electrodes is essential according to varying conduction of charge. In generally

varies from 0.6 to 1 mm.



Battery Ignition System



PROCEDURE:

Setting of Contact breaker point gap

1To adjust the contact breaker points so that the correct gap is obtained, first undo the two distributor

cap retaining screws, lift off the cap and withdraw the rotor arm from the distributor shaft. At this stage

it is a good idea to clean the inside and outside of the cap and inspect its condition. It is unlikely that

the four segments inside the cap will be badly burned or corroded, but if they are the cap must be

renewed. If only a small deposit is on the segments, it may be scraped away using a small screwdriver.

2 Push in the carbon brush located in the centre of the cap several times to ensure that it moves freely.

The brush should protrude by at least 6 mm.

3 Gently prise the contact breaker points open to examine the condition of their faces. If they are rough,

pitted or dirty it will be necessary to remove them to enable new points to be fitted.

4 Assuming that the points are in a satisfactory condition, or that they have been renewed, the gap

between the two faces should be measured using feeler blades as follows.

5 Pull off the plug leads, after marking them to ensure correct refitment, and then remove the spark

plugs.

6 With the transmission in gear and the handbrake released, slowly pull the car forward, while at the

same time watching the distributor, until the heel of the contact breaker arm is on the peak of one of the

four cam lobes. A feeler blade equal to the contact breaker points gap, as given in the Specifications,

should now just fit between the contact faces (see illustration). Make sure that the feeler blade is clean -

if the contact faces are contaminated with oil or grease, the LT current will be greatly reduced and

malfunction will result.

7 If the gap varies from this amount, slacken the contact breaker plate retaining screw and move the

breaker plate in or out to achieve the desired gap. The plate can be easily moved with a screwdriver

inserted between the notch in the breaker plate and the two adjacent pips in the distributor base plate.

8 When the gap is correct, tighten the retaining screw and then recheck the gap.

9 Refit the rotor arm, distributor cap, spark plugs and leads.

Setting of Spark Plug gap

1. Take the spark plug out of engine block.

2. Now clean the spark plug gap with the clean cloth.

3. After this use the feeler gauge to measure the gap.

4. Now increase or decrease the gap as required and again measure the gap.

5. If the gap is as required the place the spark plug at its position else repeat step 4 till the gap is

not correct.



PRACTICAL No. 7.

AIM: - Understand the working and testing of an Electronic Ignition system.

APPARATUS: - Electronic ignition systems, screw driver.

DIAGRAM: -



PRACTICAL No. 7.

AIM: - Understand the working and testing of an Electronic Ignition system.

APPARATUS: - Electronic ignition systems, screw driver.

THEORY: -

An ignition system is a system for igniting a fuel-air mixture. It is best known in the field of internal

combustion engines but also has other applications, e.g. in oil-fired and gas-fired boilers. The earliest

internal combustion engines used a flame, or a heated tube, for ignition but these were quickly replaced

by systems using an electric spark.

Electronic Ignition System

A battery ignition system has a 6- or 12-volt battery charged by an engine-driven generator to supply

electricity, an ignition coil to increase the voltage, a device to interrupt current from the coil, a

distributor to direct current to the correct cylinder, and a spark plug projecting into each cylinder.

Current goes from the battery through the primary winding of the coil, through the interrupting device,

and back to the battery.

Battery ignition system: - The system consists of two circuit, the primary and secondary circuits. In

primary circuit a battery of 6 to 12 volts, ammeter, and ignition switch, primary winding of ignition

coil, contacts breaker and condenser. The secondary circuit contains secondary winding of ignition coil,

distributor and the sparking plug.

When the contact breaker point is in closed position then the current passes through the primary

circuits develops magnetic field in the ignition coil. As soon as the contact breaker points are opened by

means of cam system the magnetic field developed in the ignition coil is collapsed suddenly, by which

a high voltage source is produced in secondary winding .this high voltage is led to each spark plug in

turn by means of distributor thus produces a spark at the electrodes of the plug. As per setting of

ignition timing. Thereby ignition the compressed charge inside the cylinder.

Components of battery ignition system:-

Metal-shell type ignition coil: - It is a transformer which steps up the 6 or 12 volts of battery to the

6000 to 20000 volts, thereby obtaining a spark the electrodes of the plug.

First the secondary coil is wound over the core and then the primary coil is done over it. The two

terminal of primary winding are taken out from the case, one of which connects to battery and other

with contact breaker arm. Out of two ends of secondary winding one is connected to spark plug through

the distributor while the other end is earthed by means of interconnection with the primary winding.

When the ignition switch is on and the contact breaker points are closed then the current from the

battery flows through the primary winding and which built up a magnetic field. When the contact

breaker in opened position then the magnetic field collapse, cut across the secondary winding and

introducing high voltage is supplied to spark plug.



Core type ignition coil:-in this type, the core is surrounded by primary winding, and then the secondary

winding is wounded on it. In this system heat is dissipates from the primary winding to the secondary

winding is controlled by means of providing a ballast resistor in the primary circuit.

Ballast resistor: - Since the primary winding is placed inside the secondary winding of the system,

therefore the length of the winding wire in primary winding is shorter than that of secondary winding.

Condenser: - As the collapsed magnetic field also cut across the primary winding when the contact

breaker points begin to open. This feedback of electrical energy is very harmful and undesirable due to

following reason. Following difficulties are overcome by condition which it produces unnecessary arc

across the contact breaker points which stores the whole feedback of electric energy and immediately

discharge it when the contact breaker points close. Thereby passing the combine current from the

battery and the condenser

Contact breaker: - It is a cam actuated automatic switch for opening and casing primary circuit at

required instant. It consists of two points made of tungsten, one is stationary or grounded point and

other is mounted on a pivoted leaver or arm. Both the points contact together by means of spring

tension. The cam is mounted on the distributer spindle which has the drive from the cam shaft. When

the cam is rotated then the level of leaver is moved up and down by lobe of cam. Thereby making and

breaking the contact between two points.

Distributer: - The main function of it is-

(a) To interrupt the flow of current is the primary winding than produces a high voltage surge in

secondary winding.

(b) To distribute is turn the high voltage surge to different flux at the right moment.

It consists of a main housing, rotating shaft with a breaker cam, contact breaker, condenser, rotor,

ignition advice mechanism and a cap having provision to install the high tension cables from ignition

coil and the spark plugs. The distributer shaft posses through the housing and gets drive from the

camshaft by means of spiral gears. The lower and of shaft is connected to oil pump. The upper end is

provided with a breaker cam which has the same number of lobes as the engine has cylindered. A rotor

is provided above the cam and at top of shaft.

Spark plug: - An element which is conduct the high potential from the ignition harness into the

combustion chamber is called spark plug. It is provided with a gap across which the high potential

discharges thereby producing a spark and burning the charge in combustion chamber.

The requirements of a good spark plug are given:-

7. It must have a high resistance so that current may be leaked thus produce spark.

8. It must maintain proper air gap between the two electrodes under all conduction.

9. It must be gas tight because leakage may cause the high temperature which results disintegration

between the insulator and electrode.

10. It must have high resistance correction thereby maintaining a proper gape length at high sparking

potential.

It must have sufficient reach length. As the long reach plug reduces and the short reach plug



11. increase combustion space.

Spark plug gap: - The factors, as the type of fuel mixture ratio and compression ratio effect the

electrical resistance of spark plug. Therefore to obtain best sparking results and adjustment of air gap

between two electrodes is essential according to varying conduction of charge. In generally varies from

0.6 to 1 mm.

PRECAUTIONS: -

1. Do not touch naked wires.

2. Dont leave naked wires cover them with cello tape.

3. Ground the wires properly.

4. Use specified wires and equipments

Complaint

1. Engine misfires on one cylinder

2. Engine misfires irregularly on all cylinders

3. Engine does not start. There is also no spark from the

coil

4. Engine gets unduly hot

Causes

a)Detached high tension cable

b)Broken wires in cable

c)Faulty spark plug

d)Large gaps in spark plugs

a)Loose L.T connection

b)Loose contact screw

c)Dirt or moisture on

distributer or ignition coil

d)Gaps of spark plug are wide

e)Leaking plugs

f)Worn out distributor Brush

and segments

a)Discharged battery

b)Circuit is open L.T wiring

c)Dirty contacts

d)Loose contact screw

e)Defective condenser

f)Defective ignition coil

a)Retarded ignition level

b)Automatic b governor not

moving freely

c)Leaky plugs

d)Incorrect timing

Remedies

a)Attach high tension cable

b)Replace the wires

c)Replace the spark plug

d)Adjust the gap to the specified

value

a)Tighten L.T connection

b)Tighten contact screw

c)Clean the distributor or ignition

coil and remove the dirt of moisture

d)Adjust the gap to the specified

value

e)Change the plugs

f)Replace the distributor brush and

segments

a)Charge the battery

b)Close the circuit

c)Clean the contacts

d)Tighten screw

e)Replace condenser

f)Replace ignition coil

a)Adjust ignition lever to the correct

position

b)Clean the parts of the governor

c)Replace plugs

d)Adjust for correct timing



PRACTICAL No. 8.

AIM: - Understand and test the lighting circuit of a car.

APPARATUS: - Horn, relay, dipper switch, flasher unit, indicator circuit, voltmeter, screw driver,

wires, fuses, soldering machine

DIAGRAM: -

Horn Circuit



PRACTICAL No. 8.

AIM: - Understand and test the lighting circuit of a car.

APPARATUS: - Horn, relay, dipper switch, flasher unit, indicator circuit, voltmeter, screw driver,

wires, fuses, soldering machine

THEORY: -

Horn: - Horn meant for producing sound. It is a sound creating device. For operating the sound

electrical energy is needed. We make use of horn in traffic places so as to get the way clear for our

vehicle to pass through that area. With the use of horns many accidents could be prevented.

Horn Relay: - A relay is usually inserted in the horn circuit. A relay is also used in some systems to

avoid carrying heavy current required by the horn through the steering column and back. The relay

closes its contacts to connect the horn to the battery. This, way the voltage drop in wiring from battery

to horn is eliminated and higher voltage is available for operating the horn with better performance. The

horn relay serves as second purpose that it gives a warning that the ignition key has been left in the car

door is opened.

Dipper Switch: - These are the switches which are used at night to get the way cleared out or to give

proper view of the road to the driver coming from front.

Flasher Unit: - The flasher unit has a thermostatic blade which expands when current from the battery

passes through it. It then wraps and open a pair of contacts thus opening the circuit. The blade cools and

straightens when there is no flow of current. In such a case circuit gets closed.

Indicator Circuit: - Indicators are used in most cars to indicate the direction in which the driver tends, to

turn his car. The lighting circuit of the directional signal is connected to that of the parking lights in the

front and rear of the car, so that the attention of other drivers, coming from the front or rear, is carefully

attracted while the car has to take a turn.

PROCEDURE:-

(A) Horn

The horn will not sound off

1) Then check the fuses, if blown off then replace fuses.

2) Then check broken circuit wire, if its broken then repair it by soldering.

If sound is of poor quality.

1) Then check the connection, if found broken repair them.

2) Then check point gap, if point gap is improper then repair is or provide proper point gap.

3) If the point is burnt them replace in withy new one.

4) Check the diaphragm if cracked then replaces it.



(B) Relay

1. Remove the horn relay from power distribution centre (PDC).

2. Using ohm meter, test for continuity between

i.Ground and circuit of horn relay. When the horn switch is not depressed, no continuity should

be present.

ii.Continuity to ground when horn switch is depressed.

iii. If continuity is not correct repair horn switch or wiring as necessary.

2) Insert a jumper wire between circuits of the power distribution center.

i. If horn sounds replace relay.

ii. If horn does not sound, install horn relay.

3) Using voltmeter, test voltage at

i. Test circuit for battery voltage.

ii. If the voltage is incorrect repair it.

4) Check the relay for 70 to 75 ohm resistance from terminals. If resistance is not correct then

replace relay.

(C) Dipper Switch

1) The filament of blub may be damaged replace it.

2) The switch circuit may be damaged replace it.

(D) Flasher Unit

1) The jumper may be broken replace it.

2) The fuse may be damaged replace it.

(E) Indicator Circuit

1) The blub may be blown up so replace it.

2) The jumper may be broken replace it.

3) The fuse may be damaged replace it.

PRECAUTIONS: -

1. Do not touch naked wires.

2. Dont leave naked wires cover them with cello tape.

3. Ground the wires properly.

4. Use specified wires and equipments.



PRACTICAL No. 9.

AIM: - Conduct headlamp focusing as per the procedure.

APPARATUS: - Vehicle, screw driver, beam adjustment chart (equipment).

DIAGRAM: -

Focusing of Headlight



PRACTICAL No. 9.

AIM: - Conduct headlamp focusing as per the procedure.

APPARATUS: - Vehicle, screw driver, beam adjustment chart (equipment).

THEORY: - The requirement of head lights for automobiles in that these should illuminate the road

ahead at reasonable distance with sufficient intensity. For this purpose reflector is used. The function of

reflector is to reflect the light which is emitted from filament into a beam of parallel rays.

PROCEDURE: -

1 Head light setting

a) The head lights have three aiming buttons on the front lens.

b) The adjustments are made by turning spring loaded screw.

c) There is one spring loaded screw at the top for up and down adjustments and one at the side

for left to right adjustment or to adjustment.

2 Beam setting

a) Place the vehicle in front of a screen/equipment at a distance of 25ft (7.62m) from it.

b) Mark the line on the screen at a distance c from the ground.

c) Mark on the screen/equipment vertical line a and b which are in line with the headlights the

distance between them being equal to the distance between headlights.

d) Cover one headlight, aiming the other.

e) On the headlights, the adjustment screws are provided. With the help of these adjust the

headlight so that the hot-spot falls on the equipments.

f) Now the headlight is aimed correctly.

g) Similarly aim the other headlight.

PRECAUTIONS: -

1) Headlight glass should be clean.

2) Ground must be perfectly level.

3) The vehicle loaded as it will be driven most of time.

aes pr

Documents

testing of battery

ignition circuit

alkaline battery

main circuit colour

battery circuit interior

ignition switch

main colour

automobile engg