Communication Fault

Communication fault

Checking communication with the gear selector module (GSM)




- Ignition on.
- Gear selector in position P
- Check whether communication with the gear selector module (GSM) works by reading off the winter mode selector (W) status.
- Connect and disconnect the function by pressing the switch. The status should change.
The fault is permanent if the value does not change.
If the value changes, this indicates that the fault is intermittent, i.e. the fault was present previously but is not active at the moment.









Continue - Checking the components and wiring

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Checking the components and wiring
Check the transmission control module (TCM) and gear selector module (GSM) connectors. Check for contact resistance and oxidation.
Check the communication cable (LIN) between the transmission control module (TCM) terminal #A7 and gear selector module (GSM) terminal #2. Check for an open-circuit.
Check the power supply cable between Gear selector module (GSM) terminal #1 and Transmission control module (TCM) terminal #16 (#A46). Check for an open-circuit.

Hint: The gear selector module (GSM) is supplied power from the transmission control module (TCM).

Check the ground lead between Gear selector module (GSM) terminal #6 and the ground terminal. Check for an open-circuit Also check the ground terminal for the ground lead.
If no fault can be found in the cable and the fault remains try replacing the printed circuit board (gear selector module (GSM)).

Hint: The gear selector module (GSM) connector can be accessed by removing the cigarette lighter/electrical outlet.

Other information
- Power socket 12V Service and Repair
- Connecting the breakout box, AW55-50/51SN Connecting Breakout Box, Transmission Control Module (TCM)
- Signal specification, AW55-50/51SN Signal Specification, Transmission Control Module (TCM)
- Top panel gear selector assembly, B5254T7, AW55-50/51SN Top Panel Gear Selector Assembly
- Checking wiring and terminals Checking Wiring and Terminals













Continue - Verification

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Verification




Verification

Hint: After carrying out the repair, check that the fault has been remedied.








- Ignition off.
- Reinstall the connectors, components etc.
- Ignition on.
- Gear selector in position P.
- Check whether communication with the gear selector module (GSM) works by reading off the winter mode selector (W) status.
Connect and disconnect the function by pressing the switch. The status should change.





Does the status change?

Yes - VERIFIED

No - VERIFICATION FAILED

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VERIFICATION FAILED - Fault-tracing information

VERIFIED - FAULT FOUND

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Fault-tracing information

Attempt New Test - Checking communication with the gear selector module (GSM)

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