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. Testing and Inspection

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 instrument cluster in order to control 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 greater than 98 percent.

CIRCUIT/SYSTEM TESTING
1. With the ignition OFF, disconnect C309.
2. With the ignition ON, install a scan tool and observe the Fuel Tank Level Remaining parameter in the ECM EVAP Data List.
- If the Fuel Tank Level Remaining parameter indicates a value less than 4 percent, check the signal circuit of the fuel level sensor for a short to ground between C309 and the fuel level sensor.
- If the fuel level sensor circuit tests normal between C309 and the fuel level sensor, replace the fuel level sensor.
- If the Fuel Tank Level Remaining parameter indicates a value greater than 4 percent, check the signal circuit of the fuel level sensor circuit for a short to ground between C309 and the ECM.
- If the fuel level sensor circuit tests normal between C309 and the ECM, replace the ECM

REPAIR INSTRUCTIONS

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