FREE REPAIR MANUALS & LABOR GUIDES 1982-2013 Vehicles
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Signal Too Low






Signal too low

Checking battery voltage








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

Other information:
- To disconnect the control module, see Replacing the gearbox control module (TCM) Replacing the Gearbox Control Module (TCM).

Select an alternative:
1. Too low voltage for both control modules.
2. Too low voltage only for the transmission control module (TCM).






1 - Checking battery voltage

2 - Checking the power supply

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Checking battery voltage




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





Was a fault detected?

Yes - Verification

No - Checking the battery terminal

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Checking the battery terminal
Check the battery positive and negative terminals and the front terminals in the engine compartment 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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FAULT-TRACING FAILED - No Fault Found

Attempt New Test - Checking battery voltage

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Checking the power supply




- Ignition off.
Check the control module connector for contact resistance and oxidation according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.
Check the power supply cable between fuse 16 in the integrated relay / fusebox in the engine compartment and #35 for an intermittent open-circuit according to Checking wiring and terminals. Intermittent faults Checking Wiring and Terminals. Intermittent Faults.

Hint: With the ignition on and the voltmeter connected between #35 and #53 on the breakout box the voltmeter should read battery voltage.

Other information:
- To connect the breakout box, see Connecting the breakout box, B5234T9, B5244T7 Connecting The Breakout Box.
- To disconnect the control module, see Replacing the gearbox control module (TCM) Replacing the Gearbox Control Module (TCM).
- For information about signals, see Signal description. Transmission control module (TCM), AW55-50/51SN Signal Description AW50-42.





Continue - Diagnostic trouble code (DTC) information

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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 - VERIFIED

No - VERIFICATION FAILED

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VERIFIED - FAULT FOUND

VERIFICATION FAILED - 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 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 - FAULT FOUND

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Attempt New Test - Checking battery voltage

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