508 ho part 11 electronic accelerator(wjb) 04-01-01

8/13/2019 508 HO Part 11 Electronic Accelerator(WJB) 04-01-01

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Fuel Supply &

ME-SFI Engine

ManagementElectronic Accelerator

(Part 11)

508 PP Part 11 Electronic Accelerator (WJB) 04-01-01


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These technical training materials are current as of the date noted on the materials, and may be revised or updated without notice.

Always check for revised or updated information.

To help avoid personal injury to you or others, and to avoid damage to the vehicle on which you are working, you must always refer

to the latest Mercedes- Benz Technical Publication and follow all pertinent instructions when testing, diagnosing or making repair.Illustrations and descriptions in this training reference are based on preliminary information and may not correspond to the final US

version vehicles. Refer to the official introduction manual and WIS when available.

Copyright Mercedes- Benz USA, LLC, 2000

Reproduction by any means or by any information storage and retrieval system or translation in whole or part is not permitted

without written authorization from Mercedes- Benz USA, LLC or its successors.

Published by Mercedes- Benz USA, LLC

Printed in U. S.A.


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Electronic Accelerator Tasks

1. Idle speed control (assisted by ignition timing)

Inputs: coolant temperature and engine load

2. Cruise control

Inputs: From traction control and cruise control switch

3. Speed limiter (RPM and VSS)


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Electronic Accelerator Tasks(Continued)

4. Reducing engine torque

Input: From traction control (ASR, ESP)

5. Reversing function - slower throttle opening

Input: From ETC control module (auto transmission)

or reverse light switch (manual transmission)

6. Emergency running (Limp home mode)


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Pedal value sensor - B37

Two versions:

PotentiometersHall effect

Hall effect only


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Potentiometers

Redundant signalsto ME.

Limp home mode

If one pot fails: throttle opening

limited to 60%

throttle delayIf both fail:

idle speed only


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Hall Type B37Note:

Only five wires Squared connector

housing

Can replace potentiometer style


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Actuator - M16

Inverse output signals to ME


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Adaptation

replacing MEcontrol module

replacing the

actuator

Adaptation to learn the

mechanical end stopmust be performed

after:Spring capsule


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PO120

ME continuously checks the signal for:

Actual value of Potentiometer 1 between 0.275 & 4.83V

Actual value of Potentiometer 2 between 0.175 & 4.74V If not okay -

Then after two consecutive driving-cycles:


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Emergency Running -

Actuator Actuator (electrical)

One potentiometer fails.

Throttle is limited to approx. 60%.

Air mass and second pot are used to calculatethrottle position

Both potentiometers fail or plausibility check fails.

Check engine light on Throttle open against spring stop (10oto 12o)

Idle speed controlled by injectors at ~900 rpm

When driving, maximum 1800 rpm


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Emergency Running (cont.)

Safety fuel shutoff -

If a mechanical fault exists in the actuator, the

safety fuel shutoff is activated.

Engine rpm limited to ~1200 rpm to 1400 rpm

by controlling the injectors.


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Acronyms

ASR - Anti Slip Regulation

ESP - Electronic Stability Program

ETC - Electronic Transmission Control

VSS - Vehicle Speed Signal

508 ho part 11 electronic accelerator(wjb) 04-01-01

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