VOLVO
ECM-A660 - Transmission control module (TCM). Signal missing
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
3 modelsC30 (2007–2013), S40 (2004–2013), V50 (2004–2013)
What does this fault code mean?
The engine control module receives the gear ratio information from the transmission over CAN. If that information is missing or faulty, the code is set. It points to the transmission control module or to the communication with it, and the driver normally notices nothing.
Possible causes
- The cause lies in the transmission control module (TCM)
What you can do
- 1Read the fault codes in the transmission control module (TCM) first, then in the central electronic module (CEM)
- 2Remedy the TCM faults and the CAN-related codes in the CEM before clearing this code
- 3Since the driver notices nothing, this code can be cleared once the faults in the TCM and CEM are gone
- 4After the repair, road test the car and check that gear changes are normal
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.