Fuel Level Sensor: Description and Operation

The fuel gauge sending unit ([1][2]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). The resistor track is used to send electrical signals to the Powertrain Control Module (PCM) for fuel gauge operation and for OBD II emission requirements.

For fuel gauge operation: As fuel level increases the float and arm move up. This decreases the sending unit resistance, causing the fuel gauge to read full. As fuel level decreases, the float and arm move down. This increases the sending unit resistance causing the fuel gauge to read empty.

After this fuel level signal is sent the the PCM, the PCM will transmit the data across the CCD bus circuit to the instrument panel. Here it is translated into the appropriate fuel gauge level reading.