General Description

Fig. 10 Level Sensor Diagnosis:

OPERATION
The fuel gauge sending unit is attached to the side of the fuel pump module. The sending unit consists of a float, an arm, and two variable resistors (tracks). These two tracks are used to send two different electrical signals. One is used for fuel gauge operation and the other is for OBD II emission requirements.

Track 1 fuel gauge operation: As the fuel level increases, the float and arm move up. This decreases the sending unit resistance, causing the fuel gauge on the instrument panel to read full. As the fuel level decreases, the float and arm move down. This increases the sending unit resistance, causing the fuel gauge on the instrument panel to read empty

Track 2-OBD II emission requirements: A variable voltage signal is sent to the PCM to indicate fuel level. The purpose of this feature is to prevent a false setting of misfire and fuel system monitor trouble codes if the fuel level in the tank is less than 15 percent of its rated capacity.

CIRCUIT OPERATION
Circuit G4 provides an input to the Powertrain Control Module (PCM) indicating fuel tank level. This circuit connects to cavity 23 of the PCM connector.

The G4 circuit is also used for the fuel gauge located in the instrument cluster. For operation of fuel gauge, Description and Operation