Diagnostic trouble code (DTC) information CEM-1A5C

Condition 

Fig 1: Identifying Rear View Mirror

Courtesy of VOLVO CARS OF NORTH AMERICA.

The diagnostic trouble code (DTC) is stored if the central electronic module (CEM) registers that communication with the upper electronic module (UEM) is not operating.

The diagnostic trouble code (DTC) can be diagnosed when the ignition has been on for more than 10 seconds.

Substitute Value 

• None.

Possible Source 

• No power supply to the upper electronic module (UEM)
• Open-circuit in the ground lead for the upper electronic module (UEM)
• Contact resistance in the terminals
• Open-circuit in the wiring for the CAN low speed network to the upper electronic module (UEM)
• The upper electronic module (UEM) is not intended for this vehicle (for example a used control module with different software/hardware).

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 controller area network (CAN). see appropriate wiring diagram. 

Fault symptom[s] 

• SRS warning light on
• Cannot be controlled with the remote control.
• The power sun roof does not operate.
• The interior lighting does not work.