Fuel Level Sensor: Description and Operation

The Fuel Lever Sensor is an important input to the Control Module for the enhanced evaporative system diagnostic. The fuel level information is needed for the Control Module to know the volume of the fuel tank. The fuel level affects the rate of charge in the air pressure in the EVAP system. Several of the Enhanced Evaporative System diagnostic sub-tests are dependent upon the correct fuel level information.

The fuel sensor is attached to the modular fuel sender. The resistance of the fuel sensor changes with the fuel level by means of a rheostat. As the position of the float varies with the fuel level, the rheostat produces a variable resistance. The fuel gauge converts this variable resistance into the fuel level reading displayed on the instrument panel.

The resistance value is sent to the Powertrain Control Module (PCM) and then sent to the Instrument Panel Cluster (IPC) and displayed on the fuel gage. It is also sent to the PCM over the Class 2 serial data circuit, and used for evaporative emission system diagnosis.