Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Fuel Level Sensor Reference Voltage Circuit | P0462 | -- | -- | P0461 |
Fuel Level Sensor Signal Circuit | P0462 | P0463 P0464 | P0463 | P0461 |
Fuel Level Sensor Low Reference Circuit | -- | P0463 P0464 | P0463 | P0461 |
Circuit/System Description
The fuel level sensor changes resistance in response to the fuel level. The powertrain control module (PCM)/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 fuel level sensor resistance is low and the PCM/ECM senses a low signal voltage. When the fuel tank is empty, the fuel level sensor resistance is high and the PCM/ECM senses a high signal voltage. The PCM/ECM uses the signal circuit of the fuel level sensor in order to calculate the percentage of fuel remaining in the tank. The PCM/ECM sends the fuel level percentage via serial data circuit to the instrument panel cluster (IPC). The PCM/ECM sends a serial data message to the IPC in order to display the fuel level in the fuel gage.
Reference Information
Schematic Reference
| • | Engine Controls Schematics for the 3.8L engine |
| • | Engine Controls Schematics for the 5.3L engine |
Connector End View Reference
| • | Powertrain Control Module Connector End Views for the 3.8L engine |
| • | Engine Control Module Connector End Views for the 5.3L engine |
Description and Operation
Instrument Cluster Description and Operation
Electrical Information Reference
Scan Tool Reference
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the fuel level sensor.
- Ignition OFF, test for less than 1 ohm of resistance between the fuel level sensor low reference circuit terminal C and ground.
- Install a Signal Generator and Instrument Panel Tester between the signal circuit terminal B and the low reference circuit terminal C.
- 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.
- 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 all circuits test normal, perform the fuel level sensor component test before replacing the fuel level sensor.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuits tests normal, replace the ECM/PCM. |
| ⇒ | If not within the specified range, test the signal circuit for an open/high resistance. If the circuit test normal, replace the ECM/PCM. |
| ⇒ | If gage is incorrect, replace the IPC. |
Component Testing
- Ignition OFF, disconnect the harness connector at the fuel level sensor.
- 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 B and the low reference terminal C.
| ⇒ | If not within the specified range, replace the fuel level sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Fuel Level Sensor Replacement for the 3.8L engine |
| • | Fuel Level Sensor Replacement for the 5.3L engine |
| • | Control Module References for the PCM/ECM replacement, setup, and programming |
