Fuel Gauge Inaccurate or Inoperative (Single Tank)
Fuel Gauge Inaccurate or Inoperative (Single Tank)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) 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 and the type of fuel in order to determine the fuel level. For regular unleaded fuel the ECM monitors a constant signal. When the vehicle has approximately 20% or greater ethanol for E85 fuel applications, the ECM controls a pulse cycle signal where it monitors the signal and calculates the fuel level percentage only during the on pulse of approximately 100 ms.
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 instrument cluster in order to control the fuel gauge.
Reference Information
Schematic Reference
Instrument Cluster Schematics (Instrument Cluster Schematics)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
Instrument Cluster Description and Operation (Instrument Cluster)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Scan Tool Reference
Control Module References (Control Module References) for scan tool information
Special Tools
J 33431-C - Instrument Panel Tester
Circuit/System Verification
Ignition ON, verify DTC P0461, P0462, P0463, or P0464 is not set
If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle).
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 fuel level sensor.
2. Ignition OFF, test for less than 1.0 ohm between the low reference circuit terminal B 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. Install a Signal Generator and Instrument Panel Tester between the signal circuit terminal C and the low reference circuit terminal B.
4. Ignition ON, vary the signal generator resistance between 40-250 ohm. 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 for an open/high resistance. If the circuits test normal, replace the ECM.
5. Vary the signal generator resistance between 40-250 ohms. Verify that the fuel gauge displays a range that varies between empty and full as the signal generator resistance changes.
• If the gauge 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, remove the fuel level sender.
2. While sweeping the fuel level sensor through its full range of motion, test for a minimum value less than 41 ohm and a maximum value greater than 119 ohm between the signal terminal C and the low reference terminal B.
• 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 (Regular Cab w/26 Gal Tank) ()Fuel Level Sensor Replacement (Extended Cab w/26 Gal Tank) ()Fuel Level Sensor Replacement (Regular Cab w/34 Gal Tank) () for the 4.3L engine
* Fuel Level Sensor Replacement (15 Reg Cab With 26 gal Tank) (Fuel Level Sensor Replacement (15 Reg Cab With 26 gal Tank))Fuel Level Sensor Replacement (15 Ext/Crew Cab With 26 gal Tank) (Fuel Level Sensor Replacement (15 Ext/Crew Cab With 26 gal Tank))Fuel Level Sensor Replacement (15 Reg/Ext/Crew Cab w/34 gal Tank) (Fuel Level Sensor Replacement (15 Reg/Ext/Crew Cab w/34 gal Tank))Fuel Level Sensor Replacement (25 Ext/Crew Cab w/26 gal Tank) (Fuel Level Sensor Replacement (25 Ext/Crew Cab w/26 Gal Tank)) for the 4.8L, 5.3L, 6.0L, and 6.2L engines
* Fuel Level Sensor Replacement () for the 6.6L engine
* Control Module References (Control Module References) for the ECM or IPC replacement, programming and setup