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 engine 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: oil pressure is low, switch to indicator light wiring has an open circuit, oil pressure switch wire connector has disconnected or on some models, 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 with the ignition switch on, replace the bulb.
If the warning light goes on when the wire is grounded to the frame or cylinder block, the engine unit should be checked for being loose or poorly grounded. If the unit is found to be tight and properly grounded, it should be removed and a new one installed. The presence of sealing compound on the threads of the engine unit will cause a poor ground.
If the warning light remains lit when it normally should be out, replace the engine unit before proceeding to determine the cause for a low pressure indication.
The warning light sometimes will light up or will flicker when the engine is idling, even though the oil pressure is adequate. However, the light should go out when the engine speed is increased. There is no cause for alarm in such cases; it simply means that the pressure switch is not calibrated precisely correct.