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 sender changes resistance in response to the fuel level. The engine control module (ECM) monitors the signal circuit of the primary fuel level sender and the secondary fuel level sender in order to determine the fuel level. When the fuel tank is full, the primary and the secondary fuel level sender resistance is low and the ECM senses a low signal voltage. When the fuel tank is empty, the primary and the secondary fuel level sender resistance is high and the ECM senses a high signal voltage. The ECM uses the signal circuit of the primary and secondary fuel level sender in order to calculate the percentage of remaining fuel in the tanks. The ECM sends the fuel level information via serial data circuit to the instrument panel cluster (IPC) for display in the fuel gage.
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
Note: If equipped, the following tests can be performed at an inline connector. See schematics for the corresponding terminals to test at.
1. Ignition OFF, disconnect the harness connector at the primary and secondary fuel level sensors.
2. Ignition OFF, test for less than 1 ohm between the primary fuel level sensor low reference circuit terminal and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
3. Ignition OFF, test for less than 1 ohm between the secondary fuel level sensor low reference circuit terminal 3 and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
4. Jumper the primary fuel level sensor signal circuit terminal 4 to the secondary fuel level sensor signal circuit terminal 4. Install a Signal Generator and Instrument Panel Tester between the jumped signal circuits and ground.
5. 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 displaying the specified range, test both signal circuits for an open/high resistance. If the circuits test normal, replace the ECM.
6. 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.
7. If all circuits test normal, perform the fuel level sensor component test before replacing either the primary or secondary fuel level sensor.
Component Testing
1. Ignition OFF, remove the primary and secondary fuel level sensors.
2. While sweeping the primary fuel level sensor through its full range of motion, test for a minimum value less than 41 ohms and a maximum value greater than 119 ohms between signal terminal 4 and the low reference terminal 3.
• If not within the specified range, replace the primary fuel level sensor.
3. While sweeping the secondary fuel level sensor through its full range of motion, test for a minimum value less than 41 ohms and a maximum value greater than 119 ohms between signal terminal 4 and the low reference terminal 3.
• If not within the specified range, replace the secondary 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 3.6L (LY7) engine
* Fuel Level Sensor Replacement (Service and Repair) for the 3.6L (LCS) engine
* Secondary Fuel Level Sensor Replacement (Service and Repair) for the 2.4L engine
* Secondary Fuel Level Sensor Replacement (Service and Repair) for the 3.5L engine
* Secondary Fuel Level Sensor Replacement (Service and Repair) for the 3.6L (LY7) engine
* Secondary Fuel Level Sensor Replacement (Service and Repair) for the 3.6L (LCS) engine
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming
* Control Module References (Programming and Relearning) for the ECM or IPC replacement, setup, and programming