All-Wheel Drive Systems - Overview. Description and Operation

The all-wheel drive system consists of the following components:

• Power Transfer Unit (PTU)
• Front and rear half shafts
• Rear axle and propshaft
• All-wheel drive relay module
• Rear axle with coupling device

Engine torque is transmitted through the transaxle to the power transfer unit (PTU). This torque is transmitted from the propshaft to the rear axle, driving the rear half shafts. The all-wheel drive system, also called the Active Torque Coupling (ATC) system, is always active and requires no driver intervention.

The all-wheel drive system continuously monitors vehicle conditions and automatically adjusts torque distribution between the front and rear wheels. During normal operation, most of the torque is delivered to the front wheels. If wheel slip is detected between the front and rear wheels, or if the vehicle is in a state of rapid acceleration or handling instability, the all-wheel drive system increases torque to the rear wheels to prevent or control wheel slip. When the all-wheel drive system is operating normally, there should be no noticeable speed difference between the front and rear axles when starting or driving the vehicle on any level surface. Traction should be similar to part-time 4WD in 4H (4X4 HIGH), but without binding in turns.

Serviceable components of the power transfer unit assembly are limited to the output shaft seal and flange, intermediate shaft seal and deflector, and the PTU case compression seal and PTU temperature sensor (if equipped). Internal components are not serviceable. The power transfer unit cover should not need to be removed. If any internal components of the PTU, bearings, case cover or shafts are worn or damaged, a new power transfer unit must be installed.

Vehicles with: ACTIVE TORQUE COUPLING DIFFERENTIAL

Vehicles with active torque coupling can be identified by the build information code EGJAE - OPEN STYLE REAR AXLE. Refer to the "Additional Information" link on the OASIS website.