For 1990-2009 cars

### 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 Circuit High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance
--- | --- | --- | --- | --- | ---
Fuel Level Sensor Signal | P0462 | 1 | P0463, P0464 | P0463 | P0461
Fuel Level Sensor Low Reference | -- | 1 | P0463, P0464 | P0463 | P0461
1. Fuel Gage Inaccurate or Inoperative

### Circuit Description

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

### Conditions for Running the DTC

The ignition is ON.

### Conditions for Setting the DTC

• | The fuel level signal is less than 1 percent.

• | The above condition is present for greater than 20 seconds.

### Action Taken When the DTC Sets

• | The fuel gage defaults to empty.

• | The LOW FUEL indicator illuminates.

• | The ECM records the operating conditions at the time the diagnostic 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.

### Reference Information

#### Schematic Reference

Instrument Cluster Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Instrument Cluster Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for Scan Tool Information

### Circuit/System Verification

Ignition ON, verify the scan tool Fuel Tank Level Remaining or Fuel Level Sensor parameter is between 4-98 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 terminal C and ground.

⇒ | If greater than the specified range, 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 terminal B and the low reference circuit terminal C. Verify the scan tool Fuel Tank Level Remaining or the Fuel Level Sensor parameter is greater than 98 percent.

⇒ | If less than the specified range, 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.

### Component Testing

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 resistance value of less than 41 ohms and a maximum value greater than 119 ohms between the 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 2.9L engine

• | Fuel Level Sensor Replacement for the 3.7L engine

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