Principles of Operation: Notes

The AWD system may be referred to as a 4WD system in other service information and owner literature.

The vehicle is equipped with an AWD system that is always active and requires no driver input.

The AWD system continuously monitors vehicle conditions and automatically adjusts the torque distribution between the front and rear wheels. During normal operation, most of the torque is delivered to the front wheels. If wheel slip between the front and rear wheels is detected, or if the vehicle is under acceleration or if the vehicle is in a handling event, the AWD system increases and distributes torque to the rear wheels as needed. When the AWD system is functioning properly, there should be no perceived speed difference between the front and rear axles when launching or driving the vehicle on any non-uniform surface. Traction should be similar to a part time 4WD system in 4H (4X4 HIGH), but have no binding in turns.

If the spare tire is installed, the AWD system may disable automatically and enter FWD to protect driveline components. This condition may be indicated by an AWD OFF message in the message center.

If there is an AWD OFF message in the message center from using the spare tire, this indicator should turn off after reinstalling the repaired or replaced normal road tire and cycling the ignition off and then on. It is recommended to reinstall the repaired or replaced road tire as soon as possible. If the tire size used on the front differ greatly from the rear the AWD system may stop functioning and default to FWD or damage to the AWD system. If this condition occurs, a DTC is set and a AWD message is displayed in the message center.

AWD faults will be indicated by the powertrain malfunction (wrench) message center warning indicator in the IPC as well as the Check AWD message center warning indicator in the message center.

The AWD system consists of a PTU, driveshaft, front and rear halfshafts, AWD relay module, PCM which includes the AWD control logic and an ATC solenoid located in the rear axle. Based on inputs to the PCM, the PCM sends a command to the AWD relay module. The amount of torque sent to the rear wheels is controlled by the AWD relay module sending a PWM duty cycle to the ATC solenoid.

NOTE: The ATC solenoid is not repairable. If a new component is required, the ATC solenoid and rear axle are installed as an assembly. Refer to REAR DRIVE AXLE/DIFFERENTIAL .

The AWD system processes data from other systems to determine the appropriate duty cycle to the AWD relay module and the ATC solenoid.

PCM inputs are:

Steering wheel angle from the SCCM via the HS-CAN
Lateral acceleration and yaw rate from the RCM via the HS-CAN
Brake system status from the ABS module via the HS-CAN
Wheel speed from the ABS module via the HS-CAN
AWD relay module diagnostic

PCM outputs are:

PWM signal to the AWD relay module
Torque transfer commanded signal to the ABS module via the HS-CAN