Oil Pressure Warning Lamp/Indicator: Testing and Inspection

On some models, the oil pressure indicator light also serves as the electric choke defect indicator. If Oil or ENG. indicator light does not light, check to ensure electric choke is not disconnected at carburetor. Also check for defect in electric choke heater, blown gauge fuse or defect in lamp or wiring circuit. If indicator light stays on with engine running possible causes are: low oil pressure, switch to indicator light open circuit, disconnected oil pressure switch connector or oil pressure gauge or radio fuse has blown.
The oil pressure warning light should go on when the ignition is turned on. If it does not light, disconnect the wire from the engine unit and ground the wire to the frame or cylinder block. Then if the warning light still does not go on, replace the bulb.
If the warning light goes on when the wire is grounded, check the engine unit for a poor ground, or improper installation. (The presence of sealing compound on the threads of the engine unit will cause a poor ground.) If the unit is found to be properly grounded and installed, replace the unit.
If the warning light remains lit when it normally should be out, replace the engine unit before proceeding to determine the cause for low pressure indication.
The warning light will sometimes light or flicker when the engine is idling, even if oil pressure is adequate. However, the light should go out when the engine speed is increased.