Engine Oil Pressure Sensor/Switch Diagnosis

Circuit Description
The powertrain control module (PCM) applies battery voltage through a pull up resistor to the engine oil pressure switch circuit. The PCM monitors the applied voltage on the engine oil pressure switch circuit. If the ignition switch is turned on with the engine not running, or the engine oil pressure is below 35 kPa (5 psi), the engine oil pressure switch grounds the PCM voltage input. The PCM sends the engine oil pressure information, via the Class 2 serial data, to the instrument panel cluster (IPC). The IPC controls the engine oil pressure indicator.

Diagnostic Aids
Inspect for the following conditions:
^ Any faulty connections. Inspect the PCM and the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connections.
^ Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the engine oil pressure switch, turn the ignition on and observe a voltmeter connected between the engine oil pressure switch connector terminals while moving the wiring harnesses related to the engine oil pressure switch circuit. A change in voltage indicates the location of the fault.