GM Service Manual Online
For 1990-2009 cars only

The movement of the steering wheel produces the following results:

  1. The movement of the steering wheel transfers to the pinion.
  2. The movement of the pinion transfers through the pinion teeth.
  3. The pinion teeth mesh with the teeth on the rack.
  4. This action causes the rack to move.

The power rack and pinion steering system has a rotary control valve. The rotary control valve directs the hydraulic fluid that flows from the hydraulic pump to either side of the rack piston.

The integral pick piston attaches to the rack.

The integral rack piston has the following effects:

  1. The rack piston converts hydraulic pressure to linear force.
  2. The linear force moves the rack left or right.
  3. The linear force transmits to the inner and outer tie rods to the steering knuckles.
  4. The steering knuckles turn the wheels.

The system will require more steering effort if hydraulic assist is not available. If hydraulic assist is not available, the system will maintain manual control.

A vane-type pump provides hydraulic pressure for the system.