VOLVO
CEM-DE23 - Communication with the trailer module (TRM). Signal missing
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?
The central module receives no communication from the trailer module (TRM), so functions controlled by it stop working. The cause may be a missing supply or earth to the module, contact resistance at connections, a break in the CAN low-speed network, or a module that is not intended for this car.
Possible causes
- No voltage supply to the trailer module (TRM)
- Open circuit in the earth lead to the trailer module (TRM)
- Contact resistance at the connections
- Open circuit in the CAN low-speed network wiring to the trailer module (TRM)
- The trailer module does not belong to this car, e.g. a used unit with other software
- Several fault codes for communication with other modules on the low-speed network point to a common fault on the CAN network
What you can do
- 1Check that the main fuse at the battery and the fuse for the trailer module are intact, using the owner's manual
- 2With a multimeter, check that the supply wire to the trailer module has no break and no contact with ground
- 3With a diagnostic tool, try to read the module ID. If it can be read, CAN communication is probably fine and the fault may be temporary
- 4If the fault remains, have a workshop check the earth point and replace the module if needed
Symptoms you may notice1
- Functions controlled by the trailer module do not work
General guidance for car owners. Diagnosis on the car can point to a different cause.