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 Power Socket 12V Power socket 12V Power Socket 12V
- Connecting the breakout box, AW55-50/51SN Connecting the Breakout Box, Transmission Control Module (TCM)
- Signal specification, AW55-50/51SN Signal Specification, Transmission Control Module (TCM)
- Printed circuit board gear selector assembly, B5254T7, AW55-50/51SN Printed Circuit Board 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 - Troubleshooting procedure complete

No - Fault-tracing information

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Fault-tracing information




Information

Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.

Do you want to exit fault-tracing?

Yes - Exit Fault-Tracing

No - Attempt New Test

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

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