The engine control module (ECM) monitors the signal circuit of the fuel level sender in order to determine fuel level. The fuel level sender consists of a variable resistor that changes resistance based on the fuel level in the tank. The ECM monitors the voltage across the sender resistance in order to determine the fuel level. When the fuel tank is full, the resistance of the fuel level sender is low and the ECM senses a low signal voltage on the signal circuit. When the fuel tank is empty, the resistance of the fuel level sender 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, in percent. The ECM sends the fuel level percent via the serial data circuit to the instrument cluster in order to control 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

Ignition ON, verify DTC P0461, P0462, 0463 or P0464 is not set.

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 3 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 2 and ground.
4. Ignition ON, vary the signal generator resistance between 40 and 250 ohms. Verify that the scan tool Fuel Tank Level Remaining or Fuel Level Sensor 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 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 gage is incorrect, replace the IPC.

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

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 ohms and a maximum value greater than 119 ohms between the signal terminal 2 and the low reference terminal 3.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.