Ford Fusion: Four-Wheel Drive Systems / Four-Wheel Drive Systems - Overview. Description and Operation

The AWD system consists of the following:

• Power transfer unit (PTU)
• Front and rear halfshafts
• Rear axle and driveshaft
• AWD relay module
• Rear axle with coupling device

Torque from the engine is transferred through the transmission to the Power Transfer Unit (PTU). This torque is transferred from the driveshaft to the rear axle, which drives the rear halfshafts. The AWD system, also referred to as an active torque coupling (ATC) system, 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 heavy acceleration, or if the vehicle is in a handling event the AWD system increases torque to the rear wheels to prevent or control wheel slip. 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 uniform surface. Traction should be similar to a part time 4WD system in 4H (4X4 HIGH), but have no binding in turns.

Serviceable components of the power transfer unit are limited to the output shaft seal and flange, intermediate shaft seal and deflector, and the power transfer unit transmission compression seal, and PTU temperature sensor (if equipped). No internal components are serviced. There should be no need to remove the power transfer unit cover. If any of the internal geared components, 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 with Build Information code EGJAE - OPEN STYLE REAR AXLE. Refer to the Additional Information link on OASIS.