Oil Pressure Warning Lamp/Indicator: Description and Operation

The low oil pressure lamp comes on to warn the driver when the engine oil pressure is low. Battery voltage is applied to one side of the bulb. A ground path is provided by the engine oil pressure switch which closes when the oil pressure is below 28 kPa (4 psi). This test the bulb when the ignition switch is turned to the RUN or START position. After the engine starts and normal oil pressure builds up the engine oil pressure switch opens and the lamp goes out.