Oil Pressure Warning Lamp/Indicator: Testing and Inspection

Combination Oil Unit (3.0L):

To test the system turn ignition key to the ON position. If the lamp fails to light, inspect for a broken or disconnected wire at the oil pressure combination unit, which is located at the front of the engine.

Combination Oil Unit Test:

If the wire at the connector checks good pull connector loose from the switch terminal and with a jumper wire ground connector to the engine. With the ignition key turned to the ON position check the warning lamp. If lamp still fails to light, inspect for a burned out bulb or disconnected socket in the cluster.

Combination Oil Unit Test:

Combination Oil Unit Test

The combination oil unit has 2 functions:

1. The normal closed circuit keeps the oil pressure warning lamp on until there is oil pressure.

2. The sending provides a resistance that varies with oil pressure.

To test the normally closed oil lamp circuit, disconnect the locking connector and measure the resistance between the switch terminal and the metal housing. The ohmmeter should read 0 ohms. Start the engine.

If there is oil pressure, the ohmmeter should read an open circuit.

To test the sending unit, measure the resistance between the sending unit terminal and the metal housing. The ohmmeter should read open. Start the engine.

The ohmmeter should read between 30 to 55 ohms, depending on engine speed, oil temperature, and oil viscosity.

If the above results are not obtained, replace the switch.