U0128

Diagnostic trouble code (DTC) information ECM-U012800

Condition
The control modules communicate with each other for exchange of information in a network via a standardized serial communication procedure - CAN (Controller Area Network).
The diagnostic trouble code (DTC) is stored if the control module detects that:
- Communication with the Park Brake Module (PBM) lost.
The control module's test for the diagnostic trouble code (DTC) starts in the event of:
- Engine running.

Note! The control module can only detect the fault once the test has been started and the diagnostic trouble code (DTC) is stored when the conditions are met. The diagnostic trouble code (DTC) indicates a fault in the communication across the CAN network and does not isolate an individual node. Do not replace the central electronic module (CEM) unless fault-tracing indicates a damaged control module.

Substitute value
- None.

Possible source
- No power supply to Park Brake Module (PBM).
- Open circuit on ground cable to Park Brake Module (PBM).
- Contact resistance in the terminals.
- Open-circuit or short-circuit in the wiring for the control area network (CAN).
- The Park Brake Module (PBM) is not intended for this vehicle, for example a used control module with different software/hardware.

Hint: If several diagnostic trouble codes for communication errors with other control modules in the high-speed network are stored in the Central electronic module (CEM), this indicates some common problem in the CAN-network (see wiring diagram).

Fault symptom[s]
- Cruise control/Does not engage