Signal Missing

Signal missing

Checking the power supply and ground




- Ignition off.
Check the fuse for the circuit. Also check the circuit after the fuse. Check for an open-circuit. Check for a short-circuit to ground.
Check the cable for power supply from Central electronic module (CEM) to Headlamp Control Module (HCM) for short-circuiting to ground as well as open circuit.
Check the cable between the grounding point and the Headlamp Control Module (HCM) for open circuit and short-circuit to voltage.
Check the grounding point to Headlamp Control Module (HCM) for contact resistance and oxidation.
Remedy as necessary.

Other information
- For connecting breakout box to Central Electronic Module (CEM): Connecting the breakout box Connecting the Breakout Box, Central Electronic Module (CEM)
- To access/replace the central electronic module (CEM):
- Headlamp Control Module (HCM) Service and Repair
- Checking wiring and terminals Checking Wiring and Terminals





Continue - Checking communication

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Checking communication

Hint: The CAN communication with the control module is probably OK if the control module ID can be read off.

Try to communicate with the Headlamp Control Module (HCM) by reading out the control module's ID.
Click the symbol for VCT2000 to begin reading off.









Is communication established?

Yes - Verification

No - Signal missing

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Signal missing

No Fault Found - No Fault Found

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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.
- Switch on the ignition for at least 10 seconds.
Check that the relevant diagnostic trouble code (DTC) has switched status from permanent to intermittent fault. Press the VCT2000 symbol.





Has the status of the diagnostic trouble code (DTC) changed?

Yes - VERIFIED

No - VERIFICATION FAILED

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VERIFIED - FAULT FOUND

VERIFICATION FAILED - Fault-tracing information

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Fault-tracing information

Attempt New Test - Checking the power supply and ground

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