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 instrument panel cluster (IPC) display on the fuel gage.

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

Scan Tool Reference

1. Ignition OFF, disconnect the harness connector at the fuel level sensors. Install a signal generator and instrument panel tester between the signal circuit and the low reference circuit.
2. Ignition ON, vary the resistance on the signal generator from 40-250 ohms. Verify that the scan tool Fuel Tank Level Remaining parameter displays the correct fuel level percent.

⇒	If the fuel level percent is incorrect, test the signal circuit and the low reference circuit for an open/high resistance. If the circuits test normal, replace the ECM.

3. Ignition ON, vary the resistance on the signal generator from 40-250 ohms and monitor the fuel gage.

⇒	If the gage is incorrect, replace the IPC.

4. If all circuits test normal, test or replace the fuel level sensors.

1. Ignition OFF, remove the fuel level senders and verify that there are no obstructions interfering with the fuel level senders.

⇒	If any interference is present, repair the fuel sender interference.

2. Ignition OFF, disconnect the harness connector at the fuel level sensors.
3. 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 the signal circuit and the low reference circuit.

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

4. 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 circuit and the low reference circuit.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.