Table C-1A Power Steering Pressure (PSP) Switch Check

Table C-1A Power Steering Pressure (PSP) Switch Check:

Power Steering Pressure (PSP) Switch:

Circuit Description

The Power Steering Pressure (PSP) switch is normally open to ground, and the Engine Control Module (ECM) 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 ECM voltage signal to read less than one volt. The ECM will increase the idle speed and prevent engine load stall.

Diagnostic Aids

An intermittent malfunction, may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Check for the following items:
- Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connections before component replacement.
- 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.
- If no problem was found, refer to Service Category Symptoms.

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table:
3. Checks for ECM signal voltage and for an open or a short to ground in signal circuit or for a faulty ECM.
4. Checks for a poor ground connection at the power steering pump and for a faulty PSP switch.