Fuel Gage Inaccurate or Inoperative

Fuel Gage Inaccurate or Inoperative

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



Diagnostic Fault Information






Circuit/System Description

The fuel level sensor changes resistance in response to the fuel level. The engine control module (ECM) 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 senses a low signal voltage. When the fuel tank is empty, the sensor resistance is high and the ECM senses a high signal voltage. The ECM uses the signal circuit of the fuel level sensor in order to calculate the percentage of remaining fuel in the tank. The ECM sends the fuel level percentage via the serial data circuit to the body control module (BCM). The BCM sends the serial data message to the instrument panel cluster (IPC) in order to control the fuel gage and display the fuel level.


Reference Information
Schematic Reference

Instrument Cluster Schematics (Instrument Cluster Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Instrument Cluster Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information
Special Tools

J 33431-C Instrument Panel Tester


Circuit/System Verification

Ignition ON, observe the scan tool Fuel Tank Level Remaining parameter. The reading should be between 4-98 percent.


Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the fuel level sensor.
2. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit terminal D and ground.

• If greater than the specified range, test the circuit for an open/high resistance. If the circuits tests normal, replace the ECM.

3. Ignition OFF, install a Signal Generator and Instrument Panel Tester between the fuel level sensor signal circuit terminal A and the low reference circuit terminal D.
4. Ignition ON, vary the signal generator resistance between 40 and 250 ohms. Verify that the scan tool Fuel Tank Level Remaining parameter displays a range that varies between 5 and 95 percent as the signal generator resistance changes.

• If not within the specified range, test the signal circuit terminal for an open/high resistance. If the circuit test normal, replace the ECM.

5. Vary the signal generator resistance between 40 and 250 ohms. Verify that the fuel gage displays a range that varies between empty and full as the signal generator resistance changes.

• If the gage is incorrect, replace the IPC.

6. If all circuits test normal, perform the fuel level sensor component test before replacing the fuel level sensor.



Component Testing

1. Ignition OFF, disconnect the harness connector at the fuel level sensor.
2. While sweeping the fuel level sensor through its full range of motion, test for a minimum value of less than 41 ohms and a maximum value greater than 119 ohms of resistance between signal terminal A and the low reference terminal D.

• If not within the specified range, replace the fuel level sensor.




Repair Instructions

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

* Fuel Level Sensor Replacement (Service and Repair) for the 2.4L engine
* Fuel Level Sensor Replacement (Service and Repair) for the 3.5L engine
* Fuel Level Sensor Replacement (Service and Repair) for the 3.9L engine
* Control Module References (Programming and Relearning) for the ECM replacement, setup and programming