Power Steering Pressure Switch: Testing and Inspection

Chart C-1E:

Chart C-1E Wiring Diagram:

CIRCUIT DESCRIPTION:

The power steering pressure switch is normally open to ground, and CKT 495 will be near 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 CKT 495 to read less than 1 volt. The ECM will increase the idle air rate and disengage the A/C relay.

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

1. Different makes of "Scan" tools may display the state of this switch in different ways. Refer to "Scan" tool operator's manual to determine how this input is indicated.

2. Checks to determine if CKT 495 is shorted to ground.

3. This should simulate a closed switch.

DIAGNOSTIC AIDS:

^ A pressure switch that will not close, or an open CKT 495 or 450, may cause the engine to stop when power steering loads are high.

^ A switch that will not open, or a CKT 495 shorted to ground may affect idle quality and will cause the A/C relay to be de-energized.