Test D: High-Speed Controller Area Network (HS-CAN) Communications Bus Fault

Pinpoint Test D: 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 control coupling (ATCC) solenoid (part of rear axle) that delivers the desired torque to the rear wheels. Specific inputs to the 4X4 control module are: accelerator pedal position output from the PCM, transmission range from the transmission control module (TCM), 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 ECM/PCM - When the 4X4 control module detects a missing HS-CAN bus message from the PCM for at least 5 seconds, this DTC is set.
^ DTC U0101 Lost Communication with TCM When the 4X4 control module detects a missing HS-CAN bus message from the TCM for at least 5 seconds, this DTC will set.
^ DTC U0121 Lost Communication with Anti-lock Brake System (ABS) Control Module - When the 4X4 control module detects a missing HS-CAN bus message from the ABS module for at least 5 seconds, this DTC is set.

This pinpoint test is intended to diagnose the following:
^ 4X4 control module
^ PCM
^ TCM
^ ABS module
^ Wiring, terminals or connectors

D1:

D2-D5:

D6-D8: