P0463

DTC P0463

DTC DESCRIPTOR
DTC P0463: Fuel Level Sensor Circuit High Voltage




DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection

CIRCUIT/SYSTEM DESCRIPTION
The fuel level sensor changes resistance in response to the fuel level. The engine control module (ECM)/powertrain control module (PCM) 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/PCM senses a low signal voltage. When the fuel tank is empty, the sensor resistance is high and the ECM/PCM senses a high signal voltage. The ECM/PCM uses the signal circuit of the fuel level sensor in order to calculate the percentage of remaining fuel in the tank. The ECM/PCM sends the fuel level percentage via GMLAN serial data circuit to the body control module (BCM). The BCM sends the fuel level information via a GMLAN serial data message to the instrument panel cluster (IPC) in order to control the fuel gage. The fuel level 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/PCM records the operating conditions at the time that the diagnostic test fails. The ECM/PCM 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/PCM 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/PCM EVAP Data List indicates a value at or greater than 4 percent.

CIRCUIT/SYSTEM TESTING
1. With the ignition OFF, disconnect C309.
2. Connect a 3-amp fused jumper wire between the signal circuit of the fuel level sensor and the low reference circuit of the fuel level sensor on the male terminal side of the connector.
3. With the ignition ON, install a scan tool and observe the Fuel Tank Level Remaining parameter in the ECM/PCM EVAP Data List.
- If the Fuel Tank Level Remaining parameter indicates a value less than 98 percent, check the signal circuit and the low reference circuit of the fuel level sensor for an open, a high resistance or a short to voltage.
- If both the signal circuit and the low reference circuit tests normal, replace the ECM/PCM.
- If the Fuel Tank Level Remaining parameter indicates a value greater than 98 percent, check the signal circuit and the low reference circuit of the fuel level sensor for an open, for a high resistance or a short to voltage between C309 and the fuel level sensor.
- If both the signal circuit and the low reference circuit tests normal between C309 and the fuel level sensor, replace the fuel level sensor.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Fuel Level Sensor Replacement for the 4.6L engine
- Fuel Level Sensor Replacement for the 3.8L engine
- Control Module References for the ECM/PCM replacement, setup and programming