Controller Area Network Data Link
WARNING: This page is about a different car, the 2009 Audi S8, 2008 Audi S8, and 2007 Audi S8. However, it is still accessible from the selected car via links, so may be relevant.
CAN is an abbreviation for Controller Area Network.
The Engine Control Module (ECM) communicates with all databus capable control modules via a CAN Data Link.
The databus capable control modules (i.e. Engine Coolant temperature Sensor) are connected via two data bus wires which are twisted together (CAN_High and CAN_Low), and exchange information (messages) to the Engine Control Module (ECM). Missing information on the databus is then recognized and stored as a malfunction.
The Engine Control Module (ECM) illuminates the Malfunction Indicator Lamp (MIL) through the CAN data link and tells the Malfunction Indicator Lamp (MIL) to turn on, turn off, or blink.