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 P0462: Fuel Level Sensor 1 Circuit Low Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance
--- | --- | --- | --- | --- | ---
Fuel Level Sensor 1 Signal | P0462 | 1 | P0463 | P0463 | P0461
Fuel Level Sensor 2 Signal | P2067 | 1 | P2068 | P2068 | P2066
Fuel Level Sensor Low Reference | -- | 1 | P0463 P2068 | P0463 P2068 | P0461 P2066
1. Fuel Gage Inaccurate or Inoperative

### 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 serial data circuit to the instrument cluster in order to control the fuel gage.

### Conditions for Running the DTC

• | The ignition is ON, with the engine running.

• | The system voltage is between 10-18 volts.

### Conditions for Setting the DTC

• | The primary fuel level signal is about 0.25 volt.

• | The above condition is present for about 60 seconds.

### Action Taken When the DTC Sets

• | The fuel gage defaults to empty.

• | The low fuel indicator displays in the IPC.

• | 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.

### 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, observe the scan tool Fuel Level Sensor parameter. The reading should be between 0.9 - 2.5 volts.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the primary fuel level sensor.
2. Ignition ON, verify that the scan tool Fuel Level Sensor Right Tank parameter is greater than 4.5 volts.

⇒ | If less than the specified range, test the primary signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the ECM.

3. If all circuits test normal, perform the fuel level sensor component test before replacing the primary fuel level sensor.

### Component Testing

1. Ignition OFF, remove the primary fuel level sender.
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 2 and the low reference terminal 4.

⇒ | If not within the specified range, replace the primary 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