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: accelerator pedal position from the powertrain control module (PCM), transmission range from the PCM, brake system status and all 4 wheel speeds from the anti-lock brake system (ABS) module. Communication between the 4X4 control module and other modules is obtained through the high speed controller area network (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.

Possible Cause

• ABS module