Diagnostic Trouble Code (DTC) Information CEM-De29
Condition
The diagnostic trouble code (DTC) is stored if the central electronic module (CEM) registers that communication with the climate control module (CCM) is not operating.
NOTE:
In the event of CEM-DEXX diagnostic trouble codes (DTCs) being stored the central electronic module (CEM) must not be replaced; the diagnostic trouble code (DTC) indicates a communication fault in the Control area network.
The diagnostic trouble code (DTC) can be diagnosed when the ignition has been on for at least 10 seconds.
Substitute Value
- None.
Possible Source
- No power supply to climate control module (CCM)
- Open-circuit in the ground lead to the climate control module (CCM)
- Contact resistance in the terminals
- Open-circuit in the wiring for the CAN low speed network to the climate control module (CCM)
- The climate control module (CCM) is not intended for this car (for example a used control module with different software/hardware).
NOTE:
In the event of missing CAN communication, but with the power supply still on, the climate control module (CCM) will function for a few minutes after the key has been removed (Limp-home function).
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.
Fault symptom[s]
- The climate control system does not function at all
- The climate control system functions after the key has been removed
- The function button is not working.