Test E: Controller Area Network (CAN) Communications Bus Fault

Pinpoint Test E: Controller Area Network (CAN) Communications Bus Fault
Refer to Vehicle/Diagrams, Four Wheel Drive (4WD) Systems for schematic and connector information.

Normal Operation
The on-demand four wheel drive (4WD) system uses data from other systems as inputs to the 4WD control module. The 4WD 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 4WD control module are: accelerator pedal 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 4WD control module and other modules is obtained through the high-speed controller area network (HS-CAN). If the 4WD control module loses communication with, or receives invalid data from any of the necessary modules, DTCs are set and the 4WD control module may not allow 4WD operation.
^ DTC U0100 Lost Communication with PCM -When the 4WD control module detects a missing HS-CAN bus message from the PCM for at least 5 seconds, this DTC is set.
^ DTC U0121 Lost Communication with ABS -When the 4WD 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:
^ 4WD control module
^ PCM
^ ABS module
^ Circuit VDB04 (WH/BU) open or short
^ Circuit VDB05 (WH) open or short
^ HS-CAN bus fault

E1-E2:

E2-E5:

E6-E7: