Checking Communication Faults

Problems with the Damper motor module (DMM) and Air quality sensor (AQS) can be because one or more of the units transmits messages on the LIN bus continuously. This means that the LIN bus is filled with messages, which, for example, can disrupt calibration of the damper motors.

The Climate control module (CCM) checks the messages in the two different LIN busses. If the Climate control module (CCM) believes that there has been a communication error on the LIB bus, a counter counts for the Damper motor module (DMM) which has sent the message.

Click the VCT2000 symbol to check if any of the Damper motor modules (DMM) have caused a new communication error on the LIN bus.

The registered communication faults read out should be interpreted as follows:

• Less than 10 registered communication errors is considered normal.
• If any of the Damper motor modules (DMM) have more than 10, but less than 100, registered communication errors, the difference with the Damper motor module (DMM) that has the next most registered communication errors must be greater than 10.
• If any of the Damper motor modules (DMM) have more than 100 registered communication errors, the difference with the Damper motor module (DMM) that has the next most registered communication errors must be greater than 100.

If no Damper motor module (DMM) meets the requirements, replace it.

Other information: 

• See Damper Motor Module (DMM) Temperature, Replacing
• See Damper Motor Module (DMM) Defroster, Replacing
• See Damper Motor Module (DMM) Recirculation, Replacing
• See Damper Motor Module (DMM) Air Distribution, Replacing

Fig 1: Identifying VCT2000

Courtesy of VOLVO CARS OF NORTH AMERICA.

Was a damaged Damper motor module (DMM) found? 

• YES 

  Refer to Checking the Function 

• NO 

  FAULT NOT FOUND:  Troubleshooting has been completed.