Diagnostic Trouble Code (DTC) Information

Diagnostic trouble code (DTC) information CEM-U016400

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:
- Interrupted or missing communication with the Climate control module (CCM).
The control module's test for the diagnostic trouble code (DTC) starts in the event of:
- Ignition switch position II.

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
- Voltage feed to Climate control module (CCM) missing.
- Open circuit on ground cable to Climate control module (CCM).
- Contact resistance in the terminals.
- Open-circuit or short-circuit in the wiring for the control area network (CAN).
- Climate control module (CCM) not intended for this car, e.g., used control module with other hardware/software.

Hint: If several diagnostic trouble codes (DTCs) are stored in the central electronic module (CEM) for communication faults with other control modules in the low speed network, this indicates a common fault in the Control area network, see the wiring diagram.

Fault symptom[s]
- Climate control does not work
- Climate control is working even after key-out
- Push button does not work