Principles of Operation: Notes

The vehicle is equipped with an All-Wheel Drive (AWD) system, also referred to as Active Torque Coupling (ATC), that is always active and requires no driver input. The system has no Mode Select Switch (MSS).

The 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 sent to the front wheels. If wheel slip between the front and rear wheels is detected or if the vehicle is under heavy acceleration (high throttle position), the AWD  system increases torque to the rear wheels to prevent or control wheel slip.

The system consists of a Power Transfer Unit (PTU), 4X4 control module, rear axle and a solenoid actuated ATC  device. Based on the amount of current sent to the clutch, the module varies the torque sent to the rear wheels by sending a duty cycle to the ATC  device, located inside the rear axle. For concerns with the PTU  , refer to TRANSFER CASE-POWER TRANSFER UNIT (PTU) .

The 4X4 control module also provides the brake system with its current clutch duty cycle and determines whether or not the brake system may take command of the clutch duty cycle.

The active, on-demand AWD  system uses data from other systems as inputs to the 4X4 control module. The 4X4 control module uses the inputs to determine the appropriate amount of current to send to the ATC  solenoid that delivers the desired torque to the rear wheels. Specific inputs to the 4X4 control module are:

• Accelerator pedal position via the High Speed Controller Area Network (HS-CAN)
• Transaxle range from the Transmission Control Module (TCM) via the HS-CAN 
• Brake system status from the ABS module via the HS-CAN 
• Wheel speed from all 4 wheels from the ABS module via the HS-CAN 

4X4 control module outputs are:

• Solid-state clutch (pulse-width modulated signal) to the ATC  solenoid
• Percent of torque transfer commanded signal to the ABS module via the HS-CAN 
• Torque request available signal to the ABS module via the HS-CAN