The power steering pressure (PSP) switch is a normally open switch located in the pressure line between the steering gear and the power steering pump. It closes when the steering system pressure reaches a high-pressure setpoint, sending a signal to the PCM to maintain engine idle speed during parking maneuvers. The Electronic Engine Control (EEC) system can detect issues with the switch and set trouble codes for specific faults. To check the operation of the PSP switch, disconnect its connector and connect an ohmmeter to the terminals on the switch body. Start the engine and let it idle, then turn the steering wheel to point the front wheels straight ahead; the ohmmeter should indicate an open circuit. As the steering wheel is turned to either side, the PSP switch should close near the steering stop, showing continuity close to zero ohms. If the switch fails either test, it should be replaced. For replacement, disconnect the electrical connector from the switch, drain the fluid from the high-pressure line using a suitable drain pan, and unscrew the switch from the high-pressure line using a back-up wrench. Finally, install and connect the new switch, bleed air from the power steering system, and add fluid as necessary.