Signal Missing or Faulty Signal

Signal missing or faulty signal

Checking the diagnostic trouble codes (DTCs)
Check whether any diagnostic trouble codes (DTCs) are stored in the brake control module (BCM) or in the central electronic module (CEM).
Any diagnostic trouble codes (DTCs) stored in the brake control module (BCM) or central electronic module (CEM) must be remedied first.

Have fault causes been traced or remedied in the brake control module (BCM) and the central electronic module (CEM)?

Yes - Checking the status

No - DONE

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Checking the status




- Ignition on
- Read off the status from the stop lamp switch.
Check the function of the stop lamp switch by carefully pressing and releasing the brake pedal.
Check that the status changes between "OFF" when the brake pedal is unaffected and "ON" when the brake pedal is depressed.
If the status of the stop lamp switch changes as described above when the brake pedal is depressed, the fault is intermittent at the moment.






Continue - Checking the power supply

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Checking the power supply




- Ignition on.
Check the power supply to the stop lamp switch. Take readings between stop lamp switch terminal #1 (cable harness side) and the ground terminal. The power supply must be approximately 12 V.

If there is no power supply:
Check the power supply circuit for stop lamp switch terminal #1 (cable harness side). Check for an open-circuit. Check for a short-circuit to ground. Check for a blown fuse in the circuit.
Remedy as necessary.

Other information:
- For further information about the fuses and relays, see the Wiring Diagram
- Connecting the breakout box, B5244T5, B5254T2 Connecting the Breakout Box
- For information about signals for 5 cylinder engines: Signal specification Signal Description / Specification
- For information about signals for 6 cylinder engines: Signal specification Signal Description / Specification
- Stop lamp switch, replacing Service and Repair
- Checking wiring and terminals Checking Wiring And Terminals.










Continue - Checking components and wiring

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Checking components and wiring




- Ignition off
- Check that the stop lamp switch is correctly installed.
Check the resistance of the stop lamp switch with the switch pressed in and with the switch released. Take readings between terminals #1 and #5 (component side) on the stop lamp switch.

Hint: The stop lamp switch must be closed when the brake pedal is depressed. The resistance of the stop lamp switch must be infinite when the brake pedal is unaffected.

Check the stop lamp switch and engine control module (ECM) connectors. Check for contact resistance and oxidation.
Check the cable between stop lamp switch terminal #5 (cable harness side) and engine control module (ECM) terminal #B26 (#B36). Check for an open-circuit. Check for a short-circuit to ground. Check for a short-circuit to supply voltage.
Check central electronic module (CEM) connector B. Check for contact resistance and oxidation.
Check the cable between stop lamp switch terminal #5 (cable harness side) and central electronic module (CEM) terminal #4B. Check for an open-circuit. Check for a short-circuit to ground. Check for a short-circuit to supply voltage.
Remedy as necessary.

Other information:
- Connecting the breakout box, B5244T5, B5254T2 Connecting the Breakout Box
- For information about signals for 5 cylinder engines: Signal specification Signal Description / Specification
- For information about signals for 6 cylinder engines: Signal specification Signal Description / Specification
- For resistance values: Component specifications Specifications
- Central electronic module (CEM), replacing Central Electronic Module (CEM), Replacing
- Checking wiring and terminals Checking Wiring And Terminals.










Continue - Verification

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Verification




Verification

Verification

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








- Ignition off
- Reconnect the connectors, reinstall components etc.
- Ignition on
- Read off the status from the stop lamp switch.
Check the function of the stop lamp switch by carefully pressing and releasing the brake pedal.
Check that the status changes between "OFF" when the brake pedal is unaffected and "ON" when the brake pedal is depressed.
If the status of the stop lamp switch changes as described above when the brake pedal is depressed, the fault has been remedied.





Is the function 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 - FAULT-TRACING FAILED

No - Attempt New Test

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FAULT-TRACING FAILED - FAULT-TRACING FAILED

Attempt New Test - Checking the diagnostic trouble codes (DTCs)

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