The primary fuel level sender and the secondary fuel level sender changes resistance based on fuel level. The engine control module (ECM) monitors the signal circuits 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 resistances of both fuel level senders are low and the ECM senses a low signal voltage on both the signal circuits of the primary fuel level sender and the secondary fuel level sender. When the fuel tanks are empty, the resistances of the fuel level senders are high and the ECM senses a high signal voltage. The ECM uses the signal circuits of the primary fuel level sender and the secondary fuel level sender 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 instrument cluster in order to control the fuel gage.

This diagnostic tests for an intermittent fuel level sender signal. If a change in fuel level is detected DTC P0442 is aborted due to a possible refueling event. A refueling event test is executed to confirm that a refueling event has occurred. If refueling is confirmed, the test for DTC P0464 is considered passing. The refueling event test must pass 2 out of 3 times, otherwise, the DTC will set indicating an intermittent signal problem.

Schematic Reference

Connector End View Reference

Description and Operation

Fuel Gage Description and Operation

Electrical Information Reference

Scan Tool Reference

Scan Tool Data List

1. Ignition OFF, disconnect the harness connector at the primary fuel level sensor.
2. Ignition OFF, test for less than 1 ohm of resistance between the primary 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 primary fuel level sensor signal circuit terminal A and ground.
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 tests normal, replace the ECM

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

1. Ignition OFF, disconnect the harness connector at the primary fuel level sensor.
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 of resistance between signal terminal A and the low reference terminal D.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.