Circuit/System Description

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