This is a normally open type of switch mounted in the pressure line of the steering gear and the power steering pump. It turns off whenever the steering system pressure gets to some high-pressure setpoint the PCM uses to control idle speed when parking. When parking the car or when the car is stationary for some time but the engine speed is high, then it would be important to check on the operation of the power steering pressure switch. This can be achieved by unplugging the switch connector and with the aid of an ohmmeter, the continuity of the switch connector can be measured by bridging across the steering wheel with the switch connector plugged. The switch should open if the front wheels are aligned in strait line when closed, they should close when the wheel is near the extreme stop position. If the switch is not able to undertake these tests successfully, then it should be changed. If the switch is okay, check the engine idle control operation and inspect the wiring harness for problems. In order to remove the switch trim the electrical connector and undo the switch from the junction block with the help of a back up wrench. Replace the switch and connect it, also, evacuate the power steering system and fill with the fluid if necessary.