VOLVO
CEM-6F85 - Dimmer. Signal too low
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?
CEM controls the brightness of the instrument lighting through an output. If the output to the instrument lighting is short-circuited to ground, the fault code is set and the instrument lighting does not work. Whether the fault is permanent or intermittent is checked by activating the lighting.
Possible causes
- Signal wire to the instrument lighting short-circuited to ground
What you can do
- 1Switch the ignition on and activate the instrument lighting; it should light at full strength when activated
- 2If it does not light, the fault is probably permanent; if it lights, the fault was present earlier but is not active now
- 3Use a multimeter to check that the control signal wire has no contact with ground (the body)
- 4Check the connectors at the light switch and at the CEM for loose connections and corrosion
- 5Remedy what is found, and if the wires are intact a workshop should replace the light switch
Symptoms you may notice1
- Instrument lighting does not work
General guidance for car owners. Diagnosis on the car can point to a different cause.