Diagnostic trouble code (DTC) information CEM-1A5A

Condition 

Fig 1: Identifying Central Electronic Module

Courtesy of VOLVO CARS OF NORTH AMERICA.

Diagnostic trouble codes (DTCs) are stored if the central electronic module (CEM) registers that communication with the rear electronic module (REM) is not operating.

Substitute Value 

None.

Possible Source 

• No power supply to rear electronic module (REM)
• Open-circuit in the ground lead to the rear electronic module (REM)
• Contact resistance in the terminals
• Open-circuit in the wiring for the CAN low speed network to the rear electronic module (REM)
• The rear electronic module (REM) is not intended for this car 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 Control area network, see appropriate wiring diagram. 

Fault symptom[s] 

• The fuel indicator indicates the minimum value even though there is fuel in the tank
• Rear demist does not operate
• Retractable headrest not operating
• No locking/unlocking of rear doors
• No unlocking of trunk lid
• The power window mechanism in the rear door does not operate.