Instrument Panel, Gauges and Warning Indicators: Testing and Inspection

When the ignition is turned to the On position current flows to the low-fuel warning sensor. If the fuel level falls below the preset level, the fuel level sensor, which is normally submerged in fuel, is exposed to air and resistance to the sensor decreases to a low level, in turn causing the warning light to go on

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.