Chart C-1A Power Steering Pressure (PSP) Switch Check

Diagnostic Chart:

Electrical Schematic:

CIRCUIT DESCRIPTION
When the Power Steering Pressure (PSP) switch is in its normally open position, Engine Control Module (ECM) terminal A19 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 a poor idling condition.

Closing the switch causes the ECM voltage signal to read less than one volt. The ECM will increase the idle air rate and prevent engine load stall.

CHART TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.
1. Checks ECM signal voltage and for an open or a short to ground in BLU/ORN wire.
2. Checks for a poor ground connection at the power steering pump and for a faulty PSP switch.

DIAGNOSTIC AIDS
A pressure switch that will not close, or loss of ground at the Power Steering Pressure switch, may cause the engine to stop when power steering loads are high.

A switch that will not open or a signal line shorted to ground may affect idle quality.

INTERMITTENT MALFUNCTIONS
An intermittent malfunction may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect harness connectors for backed out terminals, improper mating. broken locks, improperly formed or damaged terminals and poor terminal-to-wire connections before component replacement.