P0463

DTC P0463 (3.6L (LY7))

DTC Descriptor

DTC P0463
- Fuel Level Sensor 1 High Voltage

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview







Circuit/System Description

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 GMLAN serial data circuit to the instrument cluster in order to control the fuel gage. The fuel information is also used for misfire, evaporative emission (EVAP), and other onboard diagnostics.

Conditions for Running the DTC

* The engine is running.
* The system voltage is between 10-18 volts.
* Fuel level state is stable.

Conditions for Setting the DTC

* The primary fuel level signal is about 3.2 volts.
* The primary fuel level sensor signal is about 64 percent.
* The above condition is present for about 60 seconds.

Action Taken When the DTC Sets

* The fuel gage defaults to empty.
* The driver information center (DIC) displays the FUEL LEVEL LOW message.
* The ECM records the operating conditions at the time that the diagnostic test fails. The ECM displays the failure information in the Failure Records on the scan tool.

Conditions for Clearing the DTC

* The DTC becomes history when the conditions for setting the DTC are no longer present.
* The history DTC clears after 40 malfunction-free warm-up cycles.
* The ECM receives a clear code command from the scan tool.

Circuit/System Verification

With the scan tool installed and the ignition ON, the Fuel Tank Level Remaining parameter in the ECM EVAP Data List indicates a value at or greater than 4 percent.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the fuel level sensor.
2. Ignition OFF, test for less than 1 ohm of resistance between the low reference circuit and ground.

• If greater than 1 ohm, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, install a 3-amp fused jumper between the signal circuit and the low reference circuit. Verify the scan tool Fuel Tank Level Remaining parameter is greater than 98 percent.

• If less than 98 percent, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

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

Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Fuel Level Sensor Replacement - Primary for the 3.6L engine
* For the ECM replacement, setup, and programming Refer to Programming and Relearning Programming and Relearning