P0462

DTC P0462

DTC Descriptor

DTC P0462
- Fuel Level Sensor Circuit Low Voltage

Diagnostic Fault Information

Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview






Circuit/System 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 sensor resistance is high and the ECM senses a high signal voltage. When the fuel tank is empty, the sensor resistance is low and the ECM senses a low signal voltage. The ECM uses the signal circuit of the fuel level sensor in order to calculate the percentage of remaining fuel in the tank. The ECM sends the fuel level percentage via GMLAN serial data circuit to the body control module (BCM). The BCM sends a GMLAN message to the instrument panel cluster (IPC) in order to display the fuel level percent on the fuel gage. The fuel information is also used for misfire and evaporative emission (EVAP) diagnostics.

Conditions for Running the DTC

* The ignition is ON, with the engine running.
* The system voltage is between 9-16 volts.

Conditions for Setting the DTC

* The sender output is less than 0.39 volt.
* The above condition is present for greater than 30 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 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.
* The ECM receives a clear code command from the scan tool.

Circuit/System Verification

With the scan tool installed and the ignition ON, the Fuel Tank Level Remaining parameter in the ECM EVAP Data List should indicate a value at or lower than 4 percent.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the fuel level sensor.
2. Ignition ON, with the scan tool observe the Fuel Tank Level Remaining parameter. Verify the Fuel Tank Level remaining parameter is 98 percent or greater.

• If the Fuel Tank Level Remaining parameter indicates a value less than 98 percent, test the fuel level sensor signal circuit for a short to ground. If the fuel level sensor circuit tests normal, replace the ECM.

3. If all circuits tests normal, test or replace the fuel level sensor.

Repair Instructions

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

* Fuel Level Sensor Replacement for the 5.3L engine
* Fuel Sender Assembly Replacement for the 3.5L engine
* Fuel Level Sensor Replacement for the 3.9L engine
* Programming and Relearning Programming and Relearning