Fuel Level Sensor: Description and Operation

DESCRIPTION
The fuel level sensor is attached to the modular fuel sender assembly. The resistance of the fuel sensor changes with fuel level by means of a rheostat. Its range is from 90 ohms with a full tank to 0 ohms with an empty tank. This resistance value is sent to the Instrument Panel Cluster (IPC) and displayed on the fuel gage. It is also sent to the PCM over UART serial data, and used for evaporative emissions system diagnosis.

EVAP System
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 diagnostic will not run when the tank is greater than 85% or less than 1 % full. (This sensor signal will disable the misfire when the fuel levels are less than 15%.)