Oil Pressure Indicator Lamp

A warning lamp on the instrument panel is used in place of the conventional dash indicating gauge to warn the driver when oil pressure is low. The warning lamp is wired in series with the ignition switch and the oil sending unit.

The oil pressure switch contains a diaphragm and contacts. When the ignition switch is turned to the On position, the warning lamp circuit is energized and the circuit is completed through the closed contacts in the pressure switch. When the engine is started, build-up of oil pressure compresses the diaphragm, opening the contacts, thereby breaking the circuit.

TROUBLESHOOTING
When the ignition is turned On, the oil pressure warning lamp should light. If the lamp does not light, disconnect the sending unit electrical connector from the engine unit and ground wire to the frame or cylinder block. If the warning lamp still does not light with the ignition switch on, replace the bulb.

If the warning lamp lights when the wire is grounded, check the unit for looseness or improper grounding. If the unit is found to be tight and properly grounded, replace unit. If the warning lamp remains lit under normal conditions, replace the unit before proceeding further to determine the cause for a low pressure indication.

Under normal conditions, the warning lamp will sometimes light or flicker when the engine is idling. However, the lamp should go out when engine idle is raised.