Fuel Gauge

WARNING: This page is about a different car, the 2016 GMC Acadia, 2016 Chevrolet Traverse, and 2016 Buick Enclave. However, it is still accessible from the selected car via links, so may be relevant.

The fuel level sender changes resistance based on the fuel level. The 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 low and the PCM senses a low signal voltage. When the fuel tank is close to empty (above 15% remaining), the sender resistance is high and the PCM senses a high signal voltage. The PCM uses the signal circuit of the fuel level sender in order to calculate the total remaining fuel percent in the tank. The PCM sends the fuel level message via the serial data circuit to the body control module (BCM). The BCM sends the fuel level percent to the instrument panel cluster (IPC) via the serial data circuit to display on the fuel gauge. The fuel level information is also used for misfire and evaporative emission (EVAP) diagnostics. When fuel levels are less than 15% of total fuel level the PCM SWITCHES TO A CONSUMPTION MODE. The PCM stops reading the fuel level sender and instead calculates the remaining fuel level, based on fuel injector rolling counts. This is done to reduce gauge error from fuel slosh. The PCM will remain in the fuel consumption mode until enough fuel is added to raise the total fuel level to 18% or higher. The PCM will resume measuring the fuel level from the fuel level sender after a 45 second timer has expired. The timer is used to prevent driving conditions from momentarily raising the fuel level.

The fuel gauge defaults to empty if:

The ECM detects a malfunction in the fuel level sensor circuit.
The IPC detects a loss of serial data communications with the BCM
The BCM detects a loss of serial data communications with the ECM

When the fuel level is less than a pre-determined value, the low fuel indicator illuminates in the IPC.