Signal Missing

Signal missing

Checking the wiring








- Ignition off
- Disconnect central electronic module (CEM) connector C.
The diagnostic trouble code (DTC) indicates that the communication between the alternator control module (ACM) and central electronic module (CEM) is not working. This may be due to a fault in the signal cable between the control modules or a damaged communication device in one or both of the control modules.
Check the signal cable. Check for an open-circuit. Check for a short-circuit to ground.
Take readings between central electronic module (CEM) terminal #C16 (#16) and alternator control module (ACM) terminal #B1.
Remedy as necessary.

Other information
- Connecting the breakout box Connecting the Breakout Box, Central Electronic Module (CEM)
- Signal specification Signal Specification
- Location of components Locations
- Replace the generator (GEN) for gasoline engines, see: Generator, replacement Service and Repair
- Replace the generator (GEN) for diesel engines, see: Generator (GEN), replacing Service and Repair
- Checking wiring and terminals Checking Wiring And Terminals

Was a fault detected?

Yes - Verification

No - Replacing the control module

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Replacing the control module
Try a new alternator control module (ACM).
Remedy as necessary.

Other information
- Replace the generator (GEN) for gasoline engines, see: Generator, replacement Service and Repair
- Replace the generator (GEN) for diesel engines, see: Generator (GEN), replacing 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
- Start the engine and run it to normal operating temperature.
Click on the VCT2000 symbol to read off the status of the generator (GEN).
Check that the read out shows OK.





Is the status given as 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 wiring

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