VOLVO
DEM-U012900 - Lost Communication With Brake System Control Module. General Failure Information. No sub type information
System
Differential Electronic Module (DEM)
Volvo models this fault code applies to
Applies to the following models:
1 modelXC90 (2003–)
Show models by year and engine (6)
- Volvo XC90 (2003–)2005Transmission TF-80SC AWD only
- Volvo XC90 (2003–)2006Engine B8444S only · Transmission TF-80SC AWD only
- Volvo XC90 (2003–)2007–2010Engine B6324S, B8444S only · Transmission TF-80SC AWD only
- Volvo XC90 (2003–)2011Engine B6324S5, B8444S only · Transmission TF-80SC AWD only
- Volvo XC90 (2003–)2012Engine B6324S5 only · Transmission TF-80SC AWD only
- Volvo XC90 (2003–)2013–2014Engine B6324S5, D5244T18 only · Transmission TF-80SC AWD only
What does this fault code mean?
The four-wheel drive control module (DEM) gets ongoing data from the brake control module (BCM) over the CAN network, including wheel speed. If the signal from the brake control module is missing or faulty, the code is set. The fault may lie in the brake control module, in the communication cable, or in the connectors between them.
Possible causes
- Damaged brake control module (BCM)
- Damaged CAN network
- Open circuit in the communication cable
- Communication cable shorted to ground
- Communication cable shorted to voltage
- Contact resistance or oxidation in the connections
What you can do
- 1Read off the fault codes in the brake control module first and remedy them before clearing this code
- 2Check that the fuses are intact; their locations are in the owner's manual or on the fuse box cover
- 3Check the connectors and wiring in the CAN network for oxidation, loose connections and chafing
- 4If you have a diagnostic tool, check that the brake control module responds when you connect the tool
- 5Test drive the vehicle to see if the fault returns, and note whether the brakes feel different
- 6The braking system is safety-critical: if the fault remains or the brakes feel different, have a workshop check the brake control module and the CAN network
Symptoms you may notice1
- Four-wheel drive does not work
What the fault can affect1
- Four-wheel drive is disengaged
General guidance for car owners. Diagnosis on the car can point to a different cause.