Speed Proportional Steering Gear

Available on certain models of this vehicle is an electronically controlled, speed-sensitive, variable-effort, better known as speed-proportional, rack and pinion power steering system. Speed proportional power steering reduces the steering effort required by the driver for low speed driving and parking maneuvers. Also, at higher speeds, more steering effort is required providing a more firm, responsive feel to the power steering system.
With the engine running and the vehicle speed between 0 mph (0 km/h) and approximately 20 mph (32 km/h), minimum steering effort is required. Between approximately 20 mph (32 km/h) and 60 mph (100 km/h), power steering effort will gradually increase based upon vehicle speed. Above approximately 60 mph (100 km/h), maximum steering effort is required by the speed proportional steering system.

Variable-Assist Speed-Proportional Power Steering Gear:

Variable-effort power steering is provided by controlling power steering fluid pressure at the power steering gear. A solenoid control valve located on the steering gear is used to control power steering gear return fluid pressure. The pressure is controlled by varying the size of an orifice.
The variable-assist speed-proportional solenoid control valve is controlled by the Body Control Module (BCM). The BCM receives the vehicle speed signal sent from the Powertrain Control Module (PCM). Upon receiving the vehicle speed signal from the PCM, the BCM converts that speed signal into an electrical current usable by the solenoid control valve for controlling the variable effort of the power steering system.
The solenoid control valve is a serviceable component of the variable-effort, speed-proportional power steering gear assembly. It is replaceable without removal of the steering gear from the vehicle.