No communication from the control module
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2006 Volvo S80, 2005 Volvo S80, 2004 Volvo S80, 2003 Volvo S80, and 2002 Volvo S80. However, it is still accessible from the selected car via links, so may be relevant.
The central electronic module (CEM) knows which control modules should be present in the CAN network and checks at regular intervals to ensure that all control modules are communicating. If any control module in the CAN network is not communicating, a diagnostic trouble code (DTC) is stored in the central electronic module (CEM). There is a specific diagnostic trouble code (DTC) for every control module in the CAN network.