Fuel Level Sensor

The fuel gauge sending unit (fuel level sensor) is attached to the side of the fuel pump module. The sending unit consists of a float, an arm, and a variable resistor track (card). Fuel level sensor is located on fuel pump module and can be replaced separately. The fuel pump module has 4 different circuits (wires). Two of these circuits are used for the fuel gauge sending unit for fuel gauge operation, and for certain OBD-II emission requirements. The other 2 wires are used for electric fuel pump operation.

1. For Fuel Gauge Operation
   
   As fuel level increases, the float and arm move up. This increases the sending unit resistance, causing the fuel gauge to read full. As fuel level decreases, the float and arm move down. This decreases the sending unit resistance causing the fuel gauge to read empty. After this fuel level signal is sent to the instrument cluster, the instrument cluster will transmit the data across the J1850 bus circuits to the PCM.
2. OBD-II Emission Monitor Requirements
   
   The PCM will monitor the voltage output sent from the resistor track on the sending unit to indicate fuel level. The purpose of this feature is to prevent the OBD-II system from recording/setting false misfire and fuel system monitor diagnostic trouble codes.
3. The feature is activated if the fuel level in the tank is less than approximately 15 percent of its rated capacity. If equipped with a Leak Detection Pump (EVAP system monitor), this feature will also be activated if the fuel level in the tank is more than approximately 85 percent of its rated capacity.