VOLVO
CEM-8B09 - Light switch module (LSM). Faulty signal
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
5 modelsC30 (2007–2013), C30 Electric (2011–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
The CEM feeds the LSM backlighting from one output, and the module sends back a signal that the CEM compares with the outgoing one. When the two signals do not match, the code is set. This can be caused by a short circuit to supply voltage or an open circuit in the wire.
Possible causes
- The background lighting signal wire to the LSM is short-circuited to supply voltage
- Open circuit in the background lighting signal wire to the LSM
What you can do
- 1With the ignition on and the lights switched on, check whether the instrument panel lighting comes on
- 2Switch the ignition off and unplug the connector to the light switch. Check that it is clean, firmly fitted and undamaged
- 3Use a multimeter to check that the signal wire is not broken and has no contact with battery voltage
- 4If the fault remains, have a workshop check the signal wire and the module
Symptoms you may notice1
- The instrument panel lighting does not work
General guidance for car owners. Diagnosis on the car can point to a different cause.