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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