The fuel level sender changes resistance based on the fuel level. The engine control module (ECM) 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 senses a low signal voltage. When the fuel tank is empty, the sender resistance is high and the ECM senses a high signal voltage. The ECM uses the signal circuit of the fuel level sender in order to calculate the total remaining fuel percent in the tank. The ECM 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 gage.

Schematic Reference

Instrument Cluster Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Instrument Cluster Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 33431-C Instrument Panel Tester

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

⇒	If greater than the specified value, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition OFF, test for less than 1 ohm between the signal circuit terminal B and the fuel level sensor signal circuit terminal E.

⇒	If greater than the specified, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

4. Ignition OFF, install a signal generator and instrument panel tester between the signal circuit terminal D and the low reference circuit terminal B.
5. Ignition ON, vary the resistance on the signal generator from 40 to 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 the signal circuit for an open/high resistance. If the circuits test normal, replace the ECM.

6. Ignition ON, vary the resistance on the signal generator between 40 to 250 ohms. Verify that the fuel gage displays a range that varies between empty and full as the signal generator resistance changes.

⇒	If the fuel 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.

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 D and the low reference terminal B.

⇒	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 E and the low reference terminal B.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.