Signal Too Low

Signal too low

Checking the status




- Ignition on.
Activate the stop lamp.
Check if the fault is permanent or intermittent.
The stop lamp must light on activation.
The fault is permanent if the stop lamp does not activate.
If the stop lamp is activated, 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.





Continue - Checking components and wiring

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Checking components and wiring
When too low voltage has been detected, the Central electronic module (CEM) turns off the output to the next ignition cycle. If low voltage has been detected in 200 ignition cycles, the Central electronic module (CEM) is closed by the output until the DTC is erased.

Hint: Erase the diagnostic trouble code, turn off and on the ignition and read out the diagnostic trouble codes again. If the fault has disappeared, the output activates and then the brake light when the brake pedal is depressed. Otherwise the DTC will be stored again.

Check the voltage between the left and right-hand stop lamps and the output on the rear electronic module (REM). The voltage must be approximately 12 V when the stop lamp is activated.
For the S80:
Check the cable between central electronic module (CEM) terminal #A15 (15) and rear electronic module (REM) terminal #A18 (18). Check for a short-circuit to ground.
For S60, V70, XC70, and XC90:
Check the cable between central electronic module (CEM) terminal #A15 (15) and rear electronic module (REM) terminal #A18 (18). Check for a short-circuit to ground.
Check the cable between Rear electronic module (REM) and brake lights with regards to short-circuiting to ground.

Hint: Disconnect the cable between the Rear electronic module (REM) and the brake lights to ensure that the cable between the Central electronic module (CEM) and Rear electronic module (REM) is OK.

Remedy as necessary.

Other information
- Central electronic module (CEM): Connecting the breakout box Connecting The Breakout Box, Central Electronic Module (CEM)
- Rear electronic module (REM): Connecting the breakout box Connecting The Breakout Box, Rear Electronic Module (REM)
- Central electronic module (CEM): Signal specification Signal Description, Central Electronic Module (CEM)
- Rear electronic module (REM)
- Central electronic module (CEM), replacing Replacing Central Electronic Module (CEM)
- Integrated relay / fusebox cargo compartment / rear electronic module, replacing Integrated Relay/Fusebox Cargo Compartment/Rear Electronic Module (REM), Replacing
- Stop lamp high mounted, replacing 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
- Activate the stop lamps.
Check that the stop lamps are working.





Are the stop lamps working?

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 components and wiring

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