U0129

U0129

Diagnosis information - CAN

Communication, transmission control unit

NOTE: Internal function test completed.

Diagnostic conditions
The transmission control unit initially tests internal function sequences after wake-up. If they are OK, all diagnosable outputs are then tested and any faults are stored.

Transmission control unit wake-up through:
- Event-controlled CAN message
- Ignition on

Possible fault causes
- No power supply for transmission control unit
- Transmission control unit is incorrectly coded
- Short circuit or open circuit of CAN Drive
- Transmission control unit faulty (in most cases the cause is not the transmission control unit but incorrect coding.)
- DME control unit faulty

Fault effects
- No communication can take place via CAN Drive
- No other control units are able to communicate with the transmission control unit.