VOLVO
CEM-8D04 - High level stop lamp. Signal too low
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?
The central electronic module (CEM) registers a signal to the high-mounted brake light that is too low. This may be caused by the signal wire being shorted to ground. The high-mounted brake light then fails to come on when the pedal is pressed.
Possible causes
- The signal wire to the high-mounted brake light is short-circuited to ground
What you can do
- 1Press the brake with the ignition on. If the high light stays dark it is likely permanent; if it lit before, it is intermittent
- 2With the ignition off, use a multimeter to check that the wire to the high-mounted brake light has no contact with ground (the body)
- 3Look for chafing and pinched spots along the wire
- 4Clear the code and check whether it comes back
- 5If the fault returns, have a workshop check the circuit and the module
Symptoms you may notice1
- The brake lights do not come on when the pedal is pressed
General guidance for car owners. Diagnosis on the car can point to a different cause.