Circuit Description

The fuel level sender changes resistance based on the fuel level. The engine control module (ECM)/powertrain control module (PCM) monitors the signal circuit of the fuel level sender in order to determine fuel level. When the fuel tank is full, the sender resistance is high and the ECM/PCM senses a high signal voltage. When the fuel tank is empty, the sender resistance is low and the ECM/PCM senses a low signal voltage. The ECM/PCM uses the signal circuit of the fuel level sender in order to calculate the total remaining fuel percent in the tank. The ECM/PCM sends the fuel level percent via the class 2 serial data circuit to the body control module (BCM). The BCM sends that class 2 message to the instrument panel cluster (IPC) in order to display the fuel level percent on the fuel gage. The fuel level information is also used for misfire and evaporative emission (EVAP) diagnostics.

This diagnostic tests for a stuck fuel level sender signal. The ECM/PCM sets this DTC if the fuel level sender signal appears to be stuck based on a lack of signal variation expected during normal operation.