VOLVO
ECM-C122 - Communication, brake control module (BCM). Signal missing
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)
Show models by year and engine (6)
- Volvo C30 (2007–2013)2007–2010Engine D4204T only
- Volvo C70 (2006–2013)2008–2010Engine D4204T only
- Volvo S40 (2004–2013)2004–2006Engine D4204T, D4204T2 only
- Volvo S40 (2004–2013)2007–2010Engine D4204T only
- Volvo V50 (2004–2013)2004–2006Engine D4204T, D4204T2 only
- Volvo V50 (2004–2013)2007–2010Engine D4204T only
What does this fault code mean?
The engine control module monitors the signal from the brake control module (BCM) on the CAN network. The fault code is set when the signal is missing, and while the fault remains the ABS function does not work.
Possible causes
- Supply voltage to the brake control module (BCM) is missing
- Poor contact, contact resistance or oxidation in the connections
- Open circuit in the CAN line to the brake control module on the high speed side
- Internal fault in another control module on the same network section
- The brake control module is not intended for this car, for example a used unit with other software or hardware
What you can do
- 1Read out the fault codes in the CEM and the brake control module first, and fix the CAN codes before erasing anything
- 2Check that the fuses for the brake control module are intact and that the battery has a good charge
- 3Check the connectors at the brake control module and along the CAN line for play and corrosion
- 4Look for chafing or pinched sections on the wiring to the brake control module
- 5Erase the fault code once the faults are fixed, then road test the car
- 6The brake control module controls ABS. If the brakes feel uncertain, do not drive the car; have a workshop check it
Symptoms you may notice2
- A text message and warning symbol appear in the display
- Warning lamps and warning signals behave abnormally, for example the Check engine lamp
What the fault can affect1
- No ABS function
General guidance for car owners. Diagnosis on the car can point to a different cause.