VOLVO
CEM-B1C7714 - Rear Wiper Relay. General Electrical Failures. Circuit short to ground or open
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
2 modelsV40 (2013–), V40 Cross Country (2013–)
Show models by year and engine (2)
What does this fault code mean?
The central electronic module (CEM) controls the rear wiper through a relay in the engine bay fuse box. The code is set when the signal wire between the CEM and the relay is open or shorted to ground, and then the rear wiper does not work. The test only runs with the ignition in position II and the rear wiper switched off, so the fault shows when you try to use it.
Possible causes
- Open circuit on the signal wire between the CEM and the relay
- The signal wire touches ground (the bodywork) somewhere along its length
What you can do
- 1Read and clear the code, then switch the rear wiper on and see whether it runs; if the code returns the fault has not gone away
- 2Check the rear wiper fuse in the engine bay fuse box; if it is blown, find the cause before fitting a new one
- 3Look for chafing, breaks or loose connectors on the wire between the control module and the relay in the engine bay
- 4Use a multimeter to check that the wire has no contact with ground (the bodywork) and is not broken between its two ends
- 5If the wire and fuse are sound, have a workshop with diagnostic equipment check the relay control signal
Symptoms you may notice1
- The rear wiper does not work
General guidance for car owners. Diagnosis on the car can point to a different cause.