Power Steering Pressure Switch Diagnosis

Wiring Diagram:

Circuit Description
The Power Steering Pressure (PSP) switch is normally open to ground, and the Powertrain Control Module (PCM) terminal will be near battery voltage. Turning the steering wheel increases power steering oil pressure and its load on an idling engine. The PSP switch will close before the load can cause a poor idling condition. Closing the switch causes the PCM voltage signal to read less than one volt. The PCM will increase the throttle opening in order to prevent engine load stall.

Diagnostic Aids
Check for any of the following items:
^ A PSP switch that will not close, or loss of ground at the PSP switch may cause the engine to stall when power steering loads are high.
^ A PSP switch that will not open or a signal line shorted to ground may affect idle quality.
^ An intermittent malfunction may be caused by a poor connection, rubbed through wire insulation, or a broken wire inside the insulation.
^ Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connections before component replacement.

Test Description
The numbers below refer to the step numbers in the Diagnostic Table.
2. This step checks for an open or a short to ground in the YEL/BLK wire, or a faulty PCM.
3. This step checks for a faulty PCM or for a faulty A/C amplifier.