Faulty Signal

Faulty signal

Checking the status




- Ignition on
- Light switch in position 1 or position 2.
Check the voltage level from the light switch module (LSM).
Check if the fault is permanent or intermittent.
The voltage level must be changed when the instrument lighting control is altered.
The fault is permanent if the voltage level does not change.
If the voltage level changes, this is an indication that the fault was present previously but that it is not active at the moment, i.e. the fault is intermittent.
Click on the VCT2000 symbol to read off the voltage level.









Continue - Checking the component and wiring

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Checking the component and wiring
Missing function may be due to a blown fuse.
Check that the fuse for the function in question is intact.
Replace the fuse if it is damaged.
For information about fuses, see the wiring diagram.
Check the signal cable between the central electronic module (CEM) and the light switch module (LSM). Check for an open-circuit. Check for a short-circuit to ground.
Take readings between:
- Central electronic module (CEM) terminal #B21 (#21) and light switch module (LSM) terminal #9.
Remedy as necessary.

Other information
- Connecting the breakout box Connecting the Breakout Box, Central Electronic Module (CEM)
- Signal specification Signal Description, Central Electronic Module (CEM)
- Control module relay box passenger compartment Service and Repair
- Lighting switch Service and Repair
- Checking wiring and terminals Checking Wiring and Terminals









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.
Click the VCT2000 symbol to activate the lighting in the light switch.
Check that the function is OK.





Is the function OK?

Yes - Troubleshooting procedure complete

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 component and wiring

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