PSP Switch Diagnosis

Circuit Description
The Power Steering Pressure (PSP) switch is a normally open switch. When the steering wheel is turned, causing power steering pressure to increase, the PSP switch closes, pulling the switch voltage to ground. The PCM increases the idle speed in order to prevent diminished engine idle quality or engine stalling, in response to a low PSP switch signal.

Diagnostic Aids
Check for any of the following conditions:
^ A PSP switch that is shorted can cause the engine idle speed to remain high even when driving straight ahead.
^ A PSP switch that is incorrectly calibrated can cause the engine idle speed to remain low when steering pump hydraulic pressure is high.
^ A faulty ground in the PSP switch can cause erratic switch operation. Inspect that the power steering (PS) pump and bracket are secure, insuring a good path to ground. Inspect the PSP switch for a tight installation.
^ A PS pump delivering low pressure

Test Description
The numbers below refer to the step numbers in the diagnostic table.
1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
3. This step checks for voltage from the PCM or for an open or a short to ground in the PSP switch signal circuit.
4. This step checks for a inadequate ground connection at the power steering pump or a faulty PSP switch.