VOLVO
CEM-B1C5512 - Horn Relay. General Electrical Failures. Circuit short to battery
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
7 modelsS60 (2011–), S80 (2007–), V60 (2011–), V60 Cross Country (2015–), V70 (2008–), XC60 (2009–), XC70 (2008–)
What does this fault code mean?
The CEM controls the horn relay. The fault is stored when the signal to the relay drive circuit is too high, which is caused by the drive circuit being short-circuited to voltage. It is detected when the horn is activated, and the horn may then sound continuously.
Possible causes
- The relay drive circuit is short-circuited to voltage
What you can do
- 1Check that the fuse for the horn is intact
- 2Check that the horn button returns when released
- 3Clear the fault code and press the horn to see whether the fault returns
- 4Use a multimeter to check that the wire from the CEM to the horn relay is not short-circuited to battery voltage with the connectors disconnected
- 5If the fault returns, have a workshop with diagnostic equipment check the CEM and the relay
Symptoms you may notice1
- The horn sounds continuously
What the fault can affect3
- The output switches off during the driving cycle in which the fault is detected
- The output is switched off permanently after 100 driving cycles where the fault was detected
- Erasing the fault codes and starting a new driving cycle resets the output
General guidance for car owners. Diagnosis on the car can point to a different cause.