VOLVO
CEM-8FD0 - Relay, auxiliary lamp. Signal too high
System
Central Electronic Module (CEM)
Volvo models this fault code applies to
Applies to the following models:
5 modelsS60 (2001–2009), S80 (1999–2006), V70 (2000–2008), V70 XC / XC70 (2001–2007), XC90 (2003–)
What does this fault code mean?
The CEM supplies voltage to the extra lights and has registered a signal that is too high at the auxiliary lamp relay's control input. The fault shows when the relay is activated, and then the auxiliary lights do not work. The cause may be a signal cable shorted to battery voltage.
Possible causes
- Signal cable to the auxiliary lights relay shorted to battery voltage
What you can do
- 1Test the auxiliary lights with the ignition on: if they do not light the fault is permanent, and if they light it has occurred before
- 2Clear the code and check whether it returns while the auxiliary lights are activated
- 3With the ignition off, use a multimeter to check that the signal cable to the auxiliary lights relay has no contact with battery voltage
- 4Look for chafing on the cable where it may have touched battery voltage
- 5If the fault returns, have a workshop check the cable and replace the auxiliary lights relay if needed
Symptoms you may notice1
- The auxiliary lights do not work
What the fault can affect1
- After the fault has been present for a while, the output is switched off permanently until the code is cleared
General guidance for car owners. Diagnosis on the car can point to a different cause.