Power Steering Pressure Switch: Description and Operation

A Power Steering Pressure Switch (PSP Switch):
- is located on the power steering auxiliary actuator.
- sends a signal to the GEM to increase idle speed for engine stability when power steering pump pressure increases above a set pressure value.

The power steering pressure switch uses an o-ring seal. If a leak occurs at the power steering pressure switch, check that the power steering pressure switch is properly tightened to 7 - 14 Nm (62 - 123 inch lbs.). If the leak continues, replace the o-ring seal and tighten to 7 - 14 Nm (62 - 123 inch lbs.).

Check operation of the power steering pressure switch if either or both of the following concerns are noted:
- Engine stalls during parking maneuvers.
- Engine idles at high rpm.

The following test is based on the fact that the power steering pressure switch is normally closed. As power steering load increases, the power steering pressure switch opens and increases the idle speed.

1. Disconnect the electrical connector at the power steering pressure switch.
2. Connect the Rotunda 73 Digital Multimeter 105-R0051 or equivalent, across the Power Steering Pressure Switch (PSP switch) terminals.
3. Start engine and let idle.
4. Power steering pressure switch should be normally closed (zero ohms) with steering wheel straight ahead.
5. Turn steering toward either stop while watching the multimeter. Power steering pressure switch should open near the stops (no continuity or infinite reading on ohmmeter).
6. If power steering pressure switch fails either test, replace the power steering pressure switch. If power steering pressure switch is OK, check the engine idle speed control system.