Power Steering Pressure Switch: Testing and Inspection

Power Steering Pressure Switch Circuit Diagram:

CIRCUIT DESCRIPTION
The PCM applies a 12 volt reference voltage through a resistor to the Power Steering Pressure Switch (PSPS), and then monitors the voltage in the circuit. When the power steering pressure goes high, the PSPS closes, grounding the circuit and causing the measured voltage to drop to nearly zero. This indicates a power steering load on the engine. The PCM responds to this indication by disengaging the A/C compressor clutch and increasing the IAC valve counts, to compensate for the additional load on the engine during idle.

NOTE: A faulty PSPS that will not close, or an open in either the signal circuit or ground circuit may cause engine stalling under high power steering loads at idle.

A faulty PSPS that is closed all the time, or a short to ground in the signal circuit, may affect idle quality and will cause the PCM to disable the A/C compressor clutch.

TEST DESCRIPTION

Chart C-1E, Power Steering Pressure Switch Diagnosis:

Numbers below refer to circled numbers on diagnostic chart.

1. Different "SCAN" tools may display switch status differently. Refer to manufacturers operating instructions for your specific type "SCAN" tool.
2. Checks for short to ground in signal circuit.
3. Simulates a closed switch (high power steering pressure).