GM Service Manual Online
For 1990-2009 cars only

Power Steering System

The power steering system consists of 3 components: the power steering pump, the power steering fluid reservoir, and the power steering rack and pinion gear.

Power Steering Pump

The power steering pump is a vane-type pump providing hydraulic pressure for the system and is powered by the engine. The pump draws on the power steering fluid reservoir, which in turn is connected to the power steering gear. A pressure-relief valve inside the flow control valve limits the pump pressure.

Power Steering Gear

Steering wheel movement is transferred to the pinion in the steering gear. The pinion moves the rack left or right by meshing the pinion gears and the rack gears. The steering gear has a rotary control valve which directs hydraulic fluid from the power steering pump to one side or the other side of the rack piston. The integral rack piston is attached to the rack. The rack piston converts hydraulic pressure to a linear force which moves the rack to the left or the right. The force is then transmitted through the inner and the outer tie rods to the steering knuckles, which turn the wheels.

If the hydraulic assist is not available, manual control is maintained. When manual control is maintained, additional steering effort is required.