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 wiring

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Checking the wiring
Check if there are any external sources of interference near the communication cable (LIN) between the transmission control module (TCM) terminal #A7 and gear selector module (GSM) terminal #2 which can disturb communication.
Check the communication cable (LIN) for intermittent short circuits or open circuit.
Take readings between:
- Transmission control module (TCM) terminal #A7 and gear selector module (GSM) terminal #2.

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

Other information
- 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
- Power socket 12V Service and Repair













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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