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/System Description

The fuel level sender changes resistance based on the 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 percent in the tank. The ECM sends the fuel level message via the serial data circuit to the body control module (BCM). The BCM sends the fuel level percent to the instrument panel cluster (IPC) via the serial data circuit to display on the fuel gage.

### Conditions for Running the DTC

The ignition is ON, with the engine ON.

### Conditions for Setting the DTC

• | The fuel level signal is less than 3.5 percent.

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

### Action Taken When the DTC Sets

• | The fuel gage defaults to empty.

• | 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 data

### Circuit/System Verification

Ignition ON, observe the scan tool Fuel Tank Level Remaining parameter. The reading should be between 4-98 percent.

### Circuit/System Testing

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

⇒ | If greater than the specified, 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 OFF, test for less than 1 ohm between the circuit terminal C and the fuel level sensor signal circuit terminal E.

⇒ | If greater than the specified, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

4. Ignition ON, install a 3A fused jumper between the signal circuit terminal D and the low reference circuit terminal B. 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.

5. If all circuits test normal, test or replace the fuel level sensors.

### Component Testing

1. Ignition OFF, remove the primary and secondary fuel level sensors.
2. While sweeping the primary fuel level sensor through its full range of motion, test for a minimum value less than 41 ohms and a maximum value greater than 119 ohms between signal terminal D and the low reference terminal B.

⇒ | If not within the specified range, replace the primary fuel level sensor.

3. While sweeping the secondary fuel level sensor through its full range of motion, test for a minimum value less than 41 ohms and a maximum value greater than 119 ohms between signal terminal E and the low reference terminal B.

⇒ | If not within the specified range, replace the secondary fuel level sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Primary Fuel Level Sensor Replacement

• | Secondary Fuel Level Sensor Replacement

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