VOLVO
CEM-6F83 - Dimmer Faulty signal
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
This fault code has different meanings depending on model, model year or engine. Select the meaning that applies to your car.
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?
CEM registers too low or no input from the rheostat while the ignition is on and the dimmer is idle. The cause may be a rheostat short to ground, a break in the signal wire or a damaged light switch. The fault shows as instrument and button lighting that does not work.
Possible causes
- The rheostat is short-circuited to ground
- Break in the signal wire
- Damaged light switch
What you can do
- 1If you have a diagnostic tool, set the light switch to position 1 or 2 and watch the live data value while turning the dimmer; it should change
- 2If the value does not change, the fault is probably permanent; if it changes, the fault was present earlier but is not active now
- 3Use a multimeter to check that the signal wire to the dimmer has no contact with ground (the body)
- 4Check the connectors at the light switch and at the CEM for loose connections and corrosion
- 5If the wiring is intact and the fault remains, a workshop should replace the light switch
Symptoms you may notice2
- Instrument lighting or dimmer does not work
- Instrument and button lighting does not work
General guidance for car owners. Diagnosis on the car can point to a different cause.