Pinpoint Test 5: High-Speed Controller Area Network (HS-CAN) Communications Bus Fault
PINPOINT TEST 5: HIGH-SPEED CONTROLLER AREA NETWORK (HS-CAN) COMMUNICATIONS BUS FAULT
Normal Operation
The on-demand four wheel drive (4WD) system uses data from other systems as inputs to the 4X4 control module. The 4X4 control module uses the inputs to determine the appropriate duty cycle to send to the active torque coupling that delivers the desired torque to the rear wheels. Specific inputs to the 4X4 control module are: throttle position output from the PCM, transmission range from the PCM, brake system status and all 4 wheel speeds from the ABS module. Communication between the 4X4 control module and other modules is obtained through the high-speed controller area network (HS-CAN). If the 4X4 control module loses communication with, or receives invalid data from any of the necessary modules, DTCs are set and the 4X4 control module may not allow 4WD operation.
- DTC U0100 (Lost Communication with PCM) - sets when the 4X4 control module detects a missing HS-CAN bus message from the PCM for at least 5 seconds.
- DTC U0121 (Lost Communication with Anti-lock Brake System (ABS)) - sets when the 4X4 control module detects a missing HS-CAN bus message from the ABS module for at least 5 seconds.
- DTC U1900 (CAN Communication Bus Fault) - sets when the 4X4 control module does not receive ABS module or PCM HS-CAN bus messages.
Possible Causes
- 4X4 control module
- PCM
- ABS module
- Wiring, terminals or connectors
- HS-CAN bus fault
Diagnostic Procedure
NOTE:Carry out Steps 1-10 outlined in Inspection and Verification prior to carrying out this test. See Initial Inspection and Diagnostic Overview.
