VOLVO
CEM-B108786 - LIN Bus "A". Bus Signal / Message Failures. Signal invalid
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 messages on the bus are corrupted, so the connected functions may work erratically.
Possible causes
- Loose, corroded or high-resistance connections in the connectors
- The light switch module (LSM) is damaged
- The steering wheel module (SWM) is damaged
- The left steering wheel buttons (SWSL) are damaged
What you can do
- 1Read off and note the code, clear it and run the lights, indicators, wipers and washers to see which functions do not work
- 2Check that the fuses for the lighting and wiper functions are intact
- 3Check that the connectors to the light switch module and the steering wheel buttons are fully engaged 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, read the light switch and steering wheel button status in live data and check that they change when you use them
- 6If the fault remains, have a workshop check the control modules on the bus
Symptoms you may notice5
- The headlights do not work
- Front or rear turn signals do not work
- The windscreen wiper or windscreen washer does not work
- The trip computer does not work correctly
- The cruise control cannot be engaged
General guidance for car owners. Diagnosis on the car can point to a different cause.