Diagnostic trouble code (DTC) information CEM-1A55

Condition

Fig 1: Identifying Climate Control Module

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 climate control module (CCM) is not operating.

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

NOTE:

In the event of CEM-1A5X diagnostic trouble codes (DTCs), the central electronic module (CEM) must not be replaced as the diagnostic trouble code (DTC) indicates a communication fault in the controller area network (CAN).

Substitute Value

None.

Possible Source

No power supply to climate control module (CCM)
Open-circuit in the ground lead for 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 vehicle (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 controller area network (CAN). See the relevant wiring diagram.

Fault symptom[s]

The climate control system does not function at all.
The lower row of buttons on the climate control system does not function.
The climate control system functions after the key has been removed.