VOLVO
ECM-C129 - Lost Communication With Brake System Control Module
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
4 modelsC30 (2007–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
The engine control module has registered that communication with the brake control module is disturbed or missing. The fault can lie in the CAN network or in the brake control module itself, so fault-tracing starts by reading the fault codes in the brake control module.
Possible causes
- Disturbances or open circuit on the CAN network
- The cause of the fault lies in the brake control module (BCM)
What you can do
- 1Begin by reading the fault codes in the brake control module (BCM) and the CEM. Fix any CAN codes before erasing anything
- 2Check that the fuses are intact and that the battery is charged
- 3Check the connectors at the brake control module and along the CAN wires for loose contacts, corrosion and damage
- 4Look for chafing and pinched sections on the CAN wires
- 5Erase the code after the faults are fixed, then check during a road test that it does not return
- 6This fault concerns the brake control module. If the brakes or ABS feel uncertain, do not drive the car; have a workshop check it
Symptoms you may notice1
- No noticeable symptoms for the driver
General guidance for car owners. Diagnosis on the car can point to a different cause.