Four Wheel Drive System

FOUR WHEEL DRIVE SYSTEM

The 4WD system consists of the following:

- Power transfer unit (PTU). For removal and installation procedures, see - Power Transfer Unit (PTU) - Removal.
- Rear driveshaft. For removal and installation procedures, see Removal and Replacement.
- Coupling device control module (4X4 control module). For removal and installation procedures, see Service and Repair.
- Rear axle with coupling device.Torque from the engine is transferred through the transaxle to the PTU. This torque is transferred from the driveshaft to the rear axle, which drives the rear halftshaft. The AWD system, referred to as an active torque coupling (ATC) system, is always active and requires no driver input.The 4WD 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 4WD system increases torque to the rear wheels to prevent or control wheel slip.The 4X4 control module varies the torque sent to the rear wheels by varying a pulse-width modulated (PWM) current to the clutch in the rear axle. 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.Serviceable components of the PTU are limited to the output shaft seal and flange, intermediate shaft seal and deflector, and the PTU-transaxle compression seal. No internal components are serviced. There should be no need to remove the PTU cover. If any of the internal geared components, bearings, case cover or shafts are worn or damaged, a new PTU must be installed.