VOLVO
CEM-B108788 - LIN Bus "A". Bus Signal / Message Failures. Bus off
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 CEM talks to the light switch module (LSM), the left steering wheel buttons (SWSL) and the steering wheel module (SWM) over a shared LIN bus. The fault shows that the CEM cannot get its messages onto the bus, so the connected functions stop working.
Possible causes
- The LIN bus is shorted to voltage or to ground
- The light switch module (LSM) is damaged
- The left steering wheel buttons (SWSL) are damaged
- The steering wheel module (SWM) is damaged
What you can do
- 1Read off and note the code, clear it and check whether it returns when you use the lights, indicators and wipers
- 2Check that the fuses for the lighting, wiper and steering wheel functions are intact
- 3Check that the connectors to the light switch module and the steering wheel buttons are fully engaged, dry and not corroded
- 4Use a multimeter (ignition off, connectors unplugged) to check that the LIN wire has no connection to ground or to battery positive
- 5If you have a diagnostic tool, activate the indicators with the tool and check that they start
- 6If the fault remains, have a workshop check the control modules on the bus
Symptoms you may notice5
- The headlights do not work
- Turn signals do not work
- The windscreen wiper or windscreen washer does not work
- The cruise control cannot be engaged
- The trip computer does not work
General guidance for car owners. Diagnosis on the car can point to a different cause.