A power steering pressure switch is used to improve the vehicle's idle quality. The pressure switch improves vehicle idle quality by causing a readjustment of the engine idle speed as necessary when increased fluid pressure is sensed in the power steering system.
The pressure switch functions by signaling the powertrain control module that an increase in pressure of the power steering system is putting additional load on the engine. This type of condition exists when the front tires of the vehicle are turned while the vehicle is stationary and the engine is at idle speed. When the powertrain control module receives the signal from the power steering pressure switch, it directs the engine to increase its idle speed. This increase in engine idle speed compensates for the additional load, thus maintaining the required engine idle speed and idle quality.
The power steering pressure switch is mounted directly to the power steering gear
OPERATION
The switch provides an input to the PCM during periods of high pump load and low engine RPM; such as during parking maneuvers.
When power steering pump pressure exceeds 2758 kPa (400 psi), the switch is open. The PCM increases idle air flow through the IAC motor to prevent engine stalling. The PCM sends 12 volts through a resister to the sensor circuit to ground. When pump pressure is low, the switch is closed.
REMOVAL
NOTE: Before proceeding, (Refer to 19 - STEERING - WARNING).
1 - Disconnect negative battery cable from the negative post of the battery. Be sure cable is isolated from negative post on battery.
2 - Raise the vehicle. (Refer to LUBRICATION & MAINTENANCE/HOISTING - STANDARD PROCEDURE).
3 - Locate the power steering fluid pressure switch on the back side of the power steering gear (Switch Location).
4 - Remove the vehicle wiring harness connector from the power steering fluid pressure switch.
NOTE: When removing and installing the power steering pressure switch, use a 7/8 inch deep well socket. The deep well socket will prevent damage to the plastic electrical connector area of the power steering fluid pressure switch.
5 - Unscrew and remove the power steering fluid pressure switch from the power steering gear.
INSTALLATION
1 - By hand, screw the power steering pressure switch into the power steering gear until it is fully seated (Switch Location). Tighten the power steering pressure switch to a maximum torque of 8 N·m (70 in. lbs.). Over-torquing will result in stripping the threads out of the power steering pressure switch port in the steering gear.
2 - Install the vehicle wiring harness connector. Be sure the latch on the wiring harness connector is fully engaged with the locking tab on the power steering pressure switch.
3 - Lower the vehicle.
4 - Fill the power steering fluid reservoir to the correct fluid level. (Refer to 19 - STEERING/PUMP/FLUID - STANDARD PROCEDURE)
5 - Connect the negative cable to the negative post of the battery.
6 - Start the engine and turn the steering wheel several times stop-to-stop to bleed any air from the fluid in the power steering system. Stop the engine, check the fluid level, and inspect the system for leaks.
