Powertrain Control Module (PCM), NGC

P0462-FUEL LEVEL SENSOR 1 CIRCUIT LOW







Theory of Operation

The fuel level rationality will set a fault for a fuel level reading that does not change over an accumulated mileage threshold to keep stuck high or stuck low fuel levels from disabling OBD monitors. If the vehicle is fitted with a saddle tank fuel system this feature includes diagnostics for both of the sending units and diagnostics for a siphon tube that has become disconnected or plugged. The power up test looks to see a large enough fuel level voltage change from the last key-off to the following engine run. The engine run test looks to see a fuel level voltage change over an accumulated mileage.

- When Monitored:
Ignition on and battery voltage above 10.4 Volts.

- Set Condition:
The Fuel Level Sensor 1 input voltage is below the minimum acceptable value. One Trip Fault. Three good trips to turn off the MIL.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC

NOTE: Diagnose and repair any system voltage DTCs before continuing with this test.

NOTE: Diagnose and repair any communication DTCs before continuing with this test.

1. Start the engine and allow it to reach operating temperature.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

2. With the scan tool, select View DTCs.

Is the DTC Active at this time?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition Test.

2. FUEL LEVEL SENSOR
1. Turn the ignition off.
2. Disconnect the Fuel Pump Module harness connector.
3. Ignition on, engine not running.
4. With the scan tool, read the Fuel Level Sensor voltage.

Did the Fuel Level Sensor voltage change from below 0.4 of a volt to above 4.0 Volts?

Yes

- Verify that there is good pin to terminal contact at the Fuel Pump Module and the Powertrain Control Module connectors. Replace the Fuel Level Sensor if no problems were found at the connectors.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 3

3. (N4) FUEL LEVEL SIGNAL CIRCUIT SHORTED TO GROUND




1. Turn the ignition off.
2. Disconnect the C7 TIPM harness connector.
3. Measure the resistance between ground and the (N4) Fuel Level Signal circuit in the Fuel Pump Module harness connector.

Is the resistance below 100 Ohms?

Yes

- Repair the short to ground in the (N4) Fuel Level Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. EXCESSIVE RESISTANCE IN THE (N4) FUEL LEVEL SIGNAL CIRCUIT




1. Measure the resistance of the (N4) Fuel Level Signal circuit from the Fuel Pump Module harness connector to the C7 TIPM harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 5

No

- Repair the excessive resistance in the (N4) Fuel Level Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

5. TOTALLY INTEGRATED POWER MODULE
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Fuel Pump Module and the TIPM.
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the Fuel Pump Module and the TIPM connectors.
4. Search for any Technical Service Bulletins that may apply.

Were there any problems found?

Yes

- Repair as necessary.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Replace and program the TIPM.
- Perform the BODY VERIFICATION TEST. Body Verification Test.