Circuit/System Description

The fuel level sensor changes resistance in response to the fuel level. The engine control module (ECM) or the powertrain control module (PCM) monitors the signal circuit of the fuel level sensor in order to determine the fuel level. When the fuel tank is full, the sensor resistance is low and the ECM/PCM senses a low signal voltage. When the fuel tank is empty, the sensor resistance is high and the ECM/PCM senses a high signal voltage. The ECM/PCM uses the signal circuit of the fuel level sensor in order to calculate the percentage of remaining fuel in the tank. The ECM/PCM sends the fuel information to the instrument panel cluster via the GMLAN serial data circuit in order to control the fuel gage and display the fuel level. Then fuel information is also used for misfire and evaporative emission (EVAP) diagnostics.