Power Steering Pressure (PSP) Switch

The PSP switch closes in response to an increase in power steering fluid pressure (load condition). With the switch closed, a monitored voltage circuit supplied by the ECM is pulled low to vehicle ground through switch. The ECM then sends a signal to the ISC actuator to adjust idle speed to compensate for increased engine load. On Optima & Magentis (Canadian) and Rio, located on power steering pump.