For 1990-2009 cars

## DTC P0463 3.6L (LY7)

### 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.

### DTC Descriptor

DTC P0463: Fuel Level Sensor 1 High Voltage

### 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 ¹ P0464 | P0463 | P0461
Fuel Level Sensor Low Reference Circuit | -- | P0463 ¹ P0464 | P0463 | P0461
¹Fuel Gage Inaccurate or Inoperative

### Circuit/System Description

The primary fuel level sensor and the secondary fuel level sensor change resistance in response to fuel level. The engine control module (ECM) monitors the signal circuit of the primary fuel level sensor and the secondary fuel level sensor in order to determine the fuel level. When the fuel tanks are full, the resistances of both fuel level sensors are low, and the ECM senses a low signal voltage on both the signal circuit of the primary fuel level sensor and the signal circuit of the secondary fuel level sensor. When the fuel tanks are empty, the resistances of the fuel level sensors are high, and the ECM senses a high signal voltage. The ECM uses the signal circuits of the primary fuel level sensor and the secondary fuel level sensor in order to calculate the percentage of remaining fuel in the tanks. The ECM sends the fuel level percentage via the 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 on-board diagnostics.

### Conditions for Running the DTC

• | The engine is running.

• | The system voltage is between 10.5 and 18 volts.

• | Fuel level state is stable.

• | DTC P0643 runs continuously once the above condition is present for 60 seconds.

### Conditions for Setting the DTC

The primary fuel level signal is greater than 3.2 volts.

### Action Taken When the DTC Sets

• | The fuel gage defaults to empty.

• | The driver information center (DIC) displays the FUEL LEVEL LOW message.

• | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnosis runs and fails.

• | The control module records the operating conditions at the time the diagnosis fails. The first time the diagnosis fails, the control module stores this information in the Failure Records. If the diagnosis reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updated the Failure Records.

### Conditions for Clearing the DTC

• | The control module turns OFF the MIL after 4 consecutive ignition cycles that the diagnosis runs and does not fail.

• | A current DTC, Last Test Failed, is cleared when the diagnosis runs and passes.

• | A history DTC is cleared after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnosis.

• | Clear the MIL and the DTC with a scan tool.

### Reference Information

#### Fuel Level Specifications

Fuel Level Specifications

#### Schematic Reference

• | Instrument Cluster Schematics

• | Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Scan Tool Data List

### Circuit/System Verification

With the scan tool installed and the ignition ON, verify that the Fuel Tank Level Remaining parameter in the ECM EVAP Data List indicates a value at or greater than 4.9 volts.

### Circuit/System Testing

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

⇒ | If the parameter is greater than 1 ohm, test the low reference circuit for an shot to voltage or 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 Fuel Tank Level Remaining parameter of the scan tool is greater than 4.9 volts.

⇒ | If the parameter is greater than 4.8 volts, 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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Primary Fuel Level Sensor Replacement

• | Control Module References for the ECM replacement, setup, and programming

## DTC P0463 3.6L (LH2)

### 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.

### DTC Descriptor

DTC P0463: Fuel Level Sensor 1 High Voltage

### 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 ¹ P0464 | P0463 | P0461
Fuel Level Sensor Low Reference Circuit | -- | P0463 ¹ P0464 | P0463 | P0461
¹Fuel Gage Inaccurate or Inoperative

### Circuit/System Description

The primary fuel level sensor and the secondary fuel level sensor change resistance in response to fuel level. The engine control module (ECM) monitors the signal circuit of the primary fuel level sensor and the secondary fuel level sensor in order to determine the fuel level. When the fuel tanks are full, the resistances of both fuel level sensors are low, and the ECM senses a low signal voltage on both the signal circuit of the primary fuel level sensor and the signal circuit of the secondary fuel level sensor. When the fuel tanks are empty, the resistances of the fuel level sensors are high, and the ECM senses a high signal voltage. The ECM uses the signal circuits of the primary fuel level sensor and the secondary fuel level sensor in order to calculate the percentage of remaining fuel in the tanks. The ECM sends the fuel level percentage via the 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 on-board diagnostics.

### Conditions for Running the DTC

DTC P0463 runs continuously.

### Conditions for Setting the DTC

The primary fuel level sensor signal voltage is greater than 3.5 volts.

### Action Taken When the DTC Sets

• | The fuel gage defaults to empty.

• | The driver information center (DIC) displays the FUEL LEVEL LOW message.

• | DTC P0463 is a type B DTC.

### Conditions for Clearing the DTC

DTC P0463 is a type B DTC.

### Reference Information

#### Fuel Level Specifications

Fuel Level Specifications

#### Schematic Reference

• | Instrument Cluster Schematics

• | Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Scan Tool Data List

### Circuit/System Verification

With the scan tool installed and the ignition ON, verify that the Fuel Tank Level Remaining parameter in the ECM EVAP Data List indicates a value at or greater than 0.2 volt.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the fuel level sensor.
2. Ignition OFF, test for less than 1 ohm between the ground 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 wire between the signal circuit and the low reference circuit. Verify the Fuel Tank Level Remaining parameter of the scan tool is greater than 4.9 volts.

⇒ | If greater than 4.8 volts, 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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure

• | Primary Fuel Level Sensor Replacement

• | Control Module References for the ECM replacement, setup, and programming