Power Steering Fluid Flow Actuator

The power steering fluid flow actuator, mounted on the power steering pump, contains a solenoid operated valve. Discharged fluid passes through an orifice in the actuator. As the vehicle speed increases, the power steering control module increases electrical current to the fluid flow actuator. Higher current gradually moves the valve farther and farther into the orifice. This action restricts the passage of fluid flow through the orifice, reducing power assist in the steering gear. The steering pump flow ranges from 3.5 gallons per minute at idle and 0.7 gallons per minute going down the road.

When the vehicle is stationary, current through the fluid flow actuator is approximately 100 to 550 milliamps. At highway speeds, the power steering control module receives a higher frequency signal from the vehicle speeds sensor and increases the fluid flow actuator current to 600 to 850 milliamps.

Because the power steering control module sends a variable signal, the power steering fluid flow actuator provides variable levels of power assist. The EVO system therefore consistently adjusts power steering assist for changing vehicle speeds and driving conditions. For repair procedures, refer to "Power Steering Fluid Flow Actuator." For diagnosis, refer to "Diagnostic System Check."