DTC Descriptor
DTC P0463: Fuel Level Sensor Circuit High VoltageDiagnostic Instructions
Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Diagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
Fuel Level Sensor Signal Circuit | P0462 | 1 | P0463 P0464 | P0463 | P0461 |
Fuel Level Sensor Low Reference Circuit | -- | 1 | P0463 P0464 | P0463 | P0461 |
1. Fuel Gage Inaccurate or Inoperative | |||||
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 low and the ECM senses a low signal voltage. When the fuel tank is empty, the 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 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 the GMLAN message to the instrument panel cluster (IPC) in order to control the fuel gage and display the fuel level percent. Then 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 sensor output is greater than 2.9 volts. |
| • | 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. |
Reference Information
Fuel Level Specifications
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
With the scan tool installed and the ignition ON, the Fuel Tank Level Remaining parameter in the ECM EVAP Data List indicates a value at or greater than 4 percent.
Circuit/System Testing
- Ignition OFF, disconnect the fuel level sensor connector.
- Install a 3-Amp fused jumper wire between the signal circuit and the low reference circuit of the fuel level sensor. Observe the Fuel Tank Level Remaining parameter and verify the Fuel Tank Level Remaining parameter is greater than 98 percent.
- If all circuits tests normal, test or replace the fuel level sensor.
| ⇒ | If less than 98 percent, test the fuel level sensor signal and low reference circuits for a short to voltage or an open/high resistance. If the circuits test normal, replace the ECM. |
Repair Instructions
Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for the ECM replacement, setup and programming |
