Diagnostic Trouble Code (DTC) Information

Diagnostic trouble code (DTC) information CEM-DD20

Condition




The central electronic module (CEM) transmits and receives information via a standardized serial communication method - LIN (Local Interconnect Network). The diagnostic trouble code (DTC) is generated if the control module registers serious interference such as blocked LIN communication.
The diagnostic trouble code (DTC) can be detected when the ignition key is in position II for at least 10 seconds and with the battery voltage above 10.5 V.
Note: In the event of CEM-DDxx diagnostic trouble codes (DTCs), the central electronic module (CEM) must not be replaced as the diagnostic trouble code (DTC) indicates a short-circuit in one or more conductors in the LIN network. The central electronic module (CEM) is the only control module that monitors the voltage level in the LIN wiring. The central electronic module (CEM) is therefore the only control module that can generate diagnostic trouble codes (DTC) for a short-circuit in one of the cables to ground or supply voltage. Do not replace the central electronic module (CEM) in the event of a LIN fault unless fault-tracing has indicated that the central electronic module (CEM) has an internal fault.

Substitute value
- None.

Possible source
- Short-circuit between the LIN wiring
- Open-circuit in the LIN wiring
- Internal fault in another control module in the same part of the LIN network.

Fault symptom[s]
- The battery electrolyte boils when the engine is running. (Not vehicles with a V8 engine.)
- The battery discharges. (Not vehicles with a V8 engine.)
- The LED does not come on. (Only vehicles with Blind Spot Indication System, BLIS.)