Engine Oil Pressure Sensor/Switch Diagnosis

Diagnostic Chart (Part 1 Of 2):

Diagnostic Chart (Part 2 Of 2):

Schematic:

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 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 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:
^ Poor connections - Inspect PCM and harness connectors for:
- Backed out terminals
- Improper mating
- Broken locks
- Improperly formed or damaged terminals
- Poor terminal to wire connection
^ Damaged harness - Inspect the wiring harness for damage. If the harness appears to be OK, disconnect the engine oil pressure switch, turn ON the ignition and observe a DMM connected between the engine oil pressure switch connector terminals while moving wiring harnesses related to the Engine Oil Pressure Switch circuit. A change in voltage will indicate the location of the fault.

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.
15. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.