Principles of Operations

The steering wheel rotational movement is transferred to the steering gear through the steering column shaft. The steering gear converts this rotational movement, through the action of the rack and pinion gear into lateral movement. This movement in turn is transferred to the wheel knuckles through the tie-rods and tie-rod ends.

Hydraulic fluid under pressure is supplied to the steering gear by the power steering pump. As the steering wheel is rotated, the hydraulic fluid is allowed to pass through the steering gear valve to one side of a double-acting piston, dependent on which direction the steering wheel is rotated. The fluid moves the piston, which forms part of the steering gear, giving power assistance to the effort required to steer the front road wheels.

Petrol/gasolene engine variants, due to the extra load on the engine imposed by the power steering pump, have a power steering pressure (PSP) switch. The switch, which is normally closed, sends a signal to the powertrain control module (PCM) during low speed parking maneuvers. The PCM responds by maintaining the engine idle speed.