AW55-50/51SN / AW50/51 Transmission

Signal too low

Checking the battery voltage








- Ignition on
- Read off the voltage for the transmission control module (TCM) and the central electronic module (CEM).
The voltage must be battery voltage for both the control modules.

Other information:
- To disconnect the control module, see Transmission control module (TCM), replacing, B5254T2, AW50/51 AWD, B5254T2, AW55-50/51SN Service and Repair.

Select an option:
1. Voltage too low for both control modules
2. Voltage too low for the transmission control module (TCM).





1 - Checking the battery voltage

2 - Checking the power supply

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Checking the battery voltage




- Start the engine and let it run at idle speed
- Connect a voltmeter between the battery positive and negative terminals.
The voltmeter should read 12-15 V. If the voltage is lower, check the charging system for low charge voltage.





Was a fault detected?

Yes - Verification

No - Checking the battery terminals

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Checking the battery terminals
Check the battery positive and negative terminals and the front terminals in the engine compartment. Check for contact resistance and oxidation.
Remedy as necessary.

Continue - Fault-tracing information

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Fault-tracing information




Information

Fault-tracing information
The fault should be diagnosed and remedied. Since this is not the case the fault-tracing process has failed.
Complete the fault-tracing for those fault or try again.

Do you want to terminate fault-tracing at this time?

Yes - Exit fault-tracing

No - Attempt New Test

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Attempt New Test - Checking the battery voltage

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Checking the power supply




- Ignition off.
Check the transmission control module (TCM) connector and the relay for extended X supply 2/101 (located in the central electronic module (CEM)). Check for contact resistance and oxidation according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Check the power supply cable between fuse 20 in the integrated relay / fusebox in the engine compartment and the relay for extended X supply 2/101 (terminal #3 on the central electronic module CEM). Check the power supply cable between relay terminal #1 and transmission control module (TCM) terminal #A35 (#A35). Check for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. For information about the cable routing, see the relevant Wiring Diagram.

Hint: With the ignition on and voltmeter connected between transmission control module (TCM) terminals #A35 (#A35) and #A53 (#A53) the voltmeter should read battery voltage.

Other information:
- To connect the breakout box, see Connecting the breakout box, B5254T2 Connecting the Test Box
- To disconnect the control module, see Transmission control module (TCM), replacing, B5254T2, AW50/51 AWD, B5254T2, AW55-50/51SN Service and Repair
- To disconnect relay 2/101 for extended X-supply, see Central electronic module (CEM), replacing
- For information about signals, see Signal description. Transmission control module (TCM), AW55-50/51SN, AW50/51 AWD Signal Description. Transmission Control Module (TCM).





Continue - Verification

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Verification




Verification

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




- Ignition on.
- Read off the voltage for the transmission control module (TCM) and the central electronic module (CEM).
The voltage must be battery voltage for both the control modules.





Was the voltage OK?

Yes - Verification completed

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 the battery voltage

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Diagnostic trouble code (DTC) information




Information

Fault-tracing information
If the fault is intermittent, do not verify fault-tracing if the fault does not recur.
It is possible to view the information again, or leave fault-tracing for this diagnostic trouble code (DTC).

Do you want to view the information again?

Yes - Attempt New Test

No - Exit fault-tracing

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Attempt New Test - Checking the battery voltage

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