VOLVO
CEM-B1D1787 - Battery Backed Sounder. Bus Signal / Message Failures. Missing message
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
9 modelsS60 (2011–), S80 (2007–), V40 (2013–), V40 Cross Country (2013–), V60 (2011–), V60 Cross Country (2015–), V70 (2008–), XC60 (2009–), XC70 (2008–)
What does this fault code mean?
The control module (CEM) exchanges messages with the alarm siren over a shared LIN bus and checks that they arrive. The code is set when communication with the siren stops. This can be caused by an open circuit in the wiring or fuse, or by an internal fault in the siren.
Possible causes
- Open circuit in the signal wire to the alarm siren
- Open circuit in the ground wire to the alarm siren
- Open circuit in the power supply to the alarm siren
- Blown fuse
- Internal fault in the alarm siren
What you can do
- 1Read and clear the code and arm the alarm to see whether the fault returns
- 2Check that the alarm fuse is intact
- 3Look for breaks and loose connectors in the cable to the siren and at the control module
- 4Use a multimeter to check that the supply wire has voltage with the ignition off and that the ground wire has contact with the bodywork
- 5If the wiring is complete, have a workshop with diagnostic equipment check the siren and the control module
Symptoms you may notice3
- The alarm does not sound, and no visible or audible signal appears
- The alarm gives false alarms
- Yellow warning symbol and text message in the display
General guidance for car owners. Diagnosis on the car can point to a different cause.