For 1990-2009 cars

### Power Take-Off Unit (PTU) Operation

The transfer case PTU in this vehicle consists of an aluminum housing and a ring and pinion power transfer system.

The PTU transfers torque/power using an active on-demand coupling built into the rear differential design via a 1-piece propshaft assembly.

The on-demand rear differential distributes variable torque/power to the rear wheels via individual axle shafts.

The on-demand system operates as follows: the control system of the coupling monitors vehicle conditions, such as vehicle speed and wheel speeds, and commands torque to the rear wheels when depending on these variables. Typical conditions when torque is applied are during vehicle launches, even without wheel slip, and when there is front wheel slippage relative to the rear wheels. The amount of torque depends on the vehicle speed and the amount of wheel slippage.

### PTU Fluid

Note:

• | The Getrag PTU for the Sport/GXP, XL-7 Suzuki, and Saturn VUE uses synthetic differential lube.

• | For Equinox and Torrent base vehicles, use only GM Versatrak fluid in the PTU.

The PTU uses a specifically developed synthetic hypoid gear lubricant, which is intended for lifetime service. Full fluid level is at the bottom of the fill plug hole.