For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle

• | Review Strategy Based Diagnosis

• | Diagnostic Procedure Instructions

### DTC Descriptor

DTC P0464: Fuel Level Sensor Circuit Intermittent

### 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 P0460
Fuel Level Sensor Low Reference | -- | 1 | P0463 P0464 | P0463 | P0461 P0460
1. Fuel Gage Inaccurate or Inoperative

### Circuit Description

The fuel level sensor changes resistance in response to the fuel level. The engine control module (ECM) monitors the signal circuit of the fuel level sensor in order to determine the fuel level. When the fuel tank is full, the fuel level sensor resistance is low and the ECM senses a low signal voltage. When the fuel tank is empty, the fuel level sensor resistance is high and the ECM senses a high signal voltage. The ECM uses the signal circuit of the fuel level sensor in order to calculate the percentage of fuel remaining in the tank. The ECM sends the fuel level information via the serial data circuit to the IPC in order to control the fuel gage and display the fuel level.

This diagnostic tests for an intermittent fuel level sensor signal. If a change in fuel level is detected, the engine-off natural vacuum small leak test DTC P0442 is aborted due to a refueling event. Before aborting DTC P0442 a refueling event test is executed to confirm that a refueling event has occurred. If refueling is confirmed, the test is considered a pass. Otherwise, the DTC P0464 sets indicating an intermittent signal problem.

### Conditions for Running the DTC

• | The ignition is OFF.

• | DTC P0442 is running.

• | DTC P0464 runs and fails 2 out of 3 test cycles.

### Conditions for Setting the DTC

• | The fuel level change is greater than 10 percent during engine off test.

• | The above condition is present for greater than 30 seconds.

### Action Taken When the DTC Sets

• | DTC P0442 is aborted.

• | 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

#### Special Tools

J 33431-C

### Circuit/System Testing

1. Ignition OFF, disconnect the X1 harness connector at the fuel pump and sender assembly.
2. Ignition OFF, test for less than 1 ohm between the low reference circuit terminal B and ground.

⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuits tests normal, replace the ECM.

3. Install a Signal Generator and Instrument Panel Tester between the fuel level sensor signal circuit terminal C and the low reference circuit terminal B.
4. Ignition ON, vary the signal generator resistance between 40 and 250 ohms. Verify that the scan tool Displayed Fuel Level Percent parameter displays a range that varies between 5 and 95 percent as the signal generator resistance changes.

⇒ | If not displaying the specified range, test the signal circuit for an open/high resistance. If the circuit test normal, replace the ECM.

5. If all circuits test normal, perform the fuel level sensor component test before replacing 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 value less than 41 ohms and a maximum value greater than 119 ohms between signal terminal C and the low reference terminal B.

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

### Repair Instructions

Perform the Diagnostic Repair Verification

• | Fuel Level Sensor Replacement

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