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

Diagnostic Chart:




Wiring Diagram:






Circuit Description

The Power Steering Pressure (PSP) switch is normally open to ground. 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. The Powertrain Control Module (PCM) will increase the throttle valve opening to prevent an engine load stall and maintain acceptable idle quality.

The PSP switch voltage signal will read less than one volt at the PCM when the PSP switch is closed and near battery voltage at the PCM when the PSP switch is open.


Diagnostic Aids

Check for any of the following items:

^ Inspect the wiring 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.

^ An intermittent malfunction, may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation.

^ If no problem was found, Refer to Symptoms. Testing and Inspection

If any wiring repairs need to be made, Refer to Repair Procedures in Electrical Diagrams.


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. Checks for PCM signal voltage and for an open or a short to ground in signal circuit or for a faulty PCM.

4. Checks for a poor ground connection at the power steering pump and for a faulty PSP switch.