Power Steering Pressure Switch: Description and Operation

Chart C-1:

PSPS Circuit:

CIRCUIT DESCRIPTION:

The Power Steering Pressure Switch (PSPS) is normally open to ground, and ECM terminal "Y13" will be near the battery voltage. Turning the steering wheel increases power steering oil pressure and its load on an idling engine. The pressure switch will close before the load can cause an idle problem. Closing the switch causes ECM terminal "Y13" to read less than 1 volt. The ECM will increase the idle air rate and prevent engine load stall.

TEST DESCRIPTION: Numbers below refer to the circled numbers on the diagnostic chart.

1. Checks for ECM signal voltage at "Y13" and confirm good ground at PSPS housing.

2. Maximum resistance, or infinity, indicates an open switch.

3. Less than 1 ohm indicates that the switch is closed when the power steering pressure is high. Switch is OK.

DIAGNOSTIC AIDS:

A pressure switch that will not close, or an open at "Y13" or loss of ground at PSPS, may cause the engine to stop when power steering loads are high. A switch that will not open or "Y13" shorted to ground or open, may affect idle quality.