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 serial data circuit to the body control module (BCM). The BCM sends serial data messages to the instrument panel cluster (IPC) in order to control the fuel gage and display the fuel level.

Schematic Reference

Connector End View Reference

Electrical Information Reference

Scan Tool Reference

Scan Tool Data List

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 fuel level sensor low reference circuit terminal D and ground.

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

3. Install a Signal Generator and Instrument Panel Tester between the fuel level sensor signal circuit terminal A and the fuel level sensor 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 displaying the specified range, test the signal circuit 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 fuel gage is incorrect, replace the fuel gage.

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

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.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.