CAN Communications

The Engine Control Module (ECM), Electronic Brake Traction Control Module (EBTCM), and the Transaxle Control Module (TCM) communicate with each other over the CAN (controller area network) bus circuit 2501 and circuit 2500. The CAN bus is a communication link similar to class II.

The Body Control Module (BCM) acts as a gateway between the other modules connected to the class 2 serial data circuit 1807 and the ECM, EBTCM and TCM connected to the CAN bus circuit 2501 and circuit 2500.

State Of Health (SOH) messages are sent from the ECM, EBTCM and TCM to the BCM when the ignition is turned ON and during vehicle operation. These messages tell the BCM the ECM, EBTCM and TCM are working correctly. The BCM has an internal reset counter to monitor the status of the CAN bus. When the counter reaches a defined value and no CAN messages have been received from either the ECM, EBTCM or TCM, the BCM sets DTC U2104 - CAN Bus Reset Counter Overrun.