Fuel Gage Inaccurate or Inoperative

Fuel Gage Inaccurate or Inoperative

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview

Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Diagnostic Procedure Instructions provide an overview of each diagnostic category.

Circuit/System 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 low and the ECM/PCM senses a low signal voltage. When the fuel tank is empty, the sender resistance is high and the ECM/PCM senses a high 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 message via the CAN serial data circuit to the body control module (BCM). The BCM sends the fuel level percent to the instrument panel cluster (IPC) via the class 2 data circuit to display on the fuel gage. The fuel level information is also used for misfire and evaporative emission (EVAP) diagnostics.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the fuel level sensors. Install a signal generator and instrument panel tester between the signal circuit and the low reference circuit.
2. Ignition ON, vary the resistance on the signal generator from 40 to 250 ohms. Verify that the scan tool Fuel Tank parameter displays the correct fuel level.

• If the fuel level is incorrect, test the signal circuit and the low reference circuit for an open/high resistance. If the circuits test normal, replace the ECM/PCM.

3. Ignition ON, vary the resistance on the signal generator from 40 to 250 ohms and monitor the fuel gage.

• If the gage is incorrect, replace the IPC.

4. If all circuits test normal, test or replace the fuel level sensors.

Component Testing

Measure the resistance of the float arm of the fuel level sender while moving the float arm between 40-250 ohms.

If the resistance does not move smoothly across the specified range, replace the fuel level sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Fuel Level Sensor Replacement (Primary) Fuel Level Sensor Replacement (Secondary) for the 2.2L engine
* Fuel Level Sensor Replacement (Primary) Fuel Level Sensor Replacement (Secondary) for the 2.4L engine
* Primary Fuel Level Sensor Replacement for the 3.5L engine
* Fuel Level Sensor Replacement - Secondary for the 3.5L engine
* Control Module References for ECM/PCM replacement, setup, and programming