Power Transfer Unit - Overview: Notes

The AWD system consists of the following:

• Power Transfer Unit (PTU)
• Rear driveshaft
• AWD control module
• Rear axle with coupling device

The Power Transfer Unit (PTU) is a gearbox that attaches to the transmission. The PTU directs power to the rear driveshaft through a helical gear spline coupled to the transmission differential case and hypoid/helical ring gear assembly and pinion set. It supplies torque to the rear axle through the rear driveshaft. The AWD control module is an electronic device which controls the rear axle coupling to apply the torque generated from the Power Transfer Unit (PTU) to the rear wheels when required. On AWD vehicles the intermediate shaft passes through the PTU and engages the differential side gears. The serviceability of the Power Transfer Unit (PTU) is limited to the input shaft seal LH, input shaft seal RH, intermediate shaft seal, transfer case rear seal, cover seal, face seal, vent hose and the output flange deflector. If any internal damage is present the Power Transfer Unit (PTU) must be replaced as a sealed unit.