Displays and Gages (W/O Delphi Controller)

DTC P0462 (w/o Delphi Controller)

Circuit Description

The fuel level sensor changes resistance based on the amount of fuel in the fuel tank. The fuel level sensor has a common, or shared 5-volt reference circuit and a signal circuit. The engine control module (ECM) applies 5 volts on the reference circuit to the sensor. The ECM monitors the changes in this voltage on the signal circuit, caused by a change in the resistance of the fuel level sensor, in order to determine fuel level. The fuel level sensor is part of the fuel sender, and is serviced as an assembly.

When the fuel tank is full, the sensor resistance is low, and the ECM signal voltage is high. When the fuel tank is empty, the sensor resistance is high, and the signal voltage is low.

The ECM uses inputs from the fuel level sensor in order to calculate the total fuel percentage remaining in the fuel tank. The ECM uses the fuel level information for the EVAP and misfire diagnostics. The fuel level information is sent to the instrument panel cluster (IPC).

If the ECM detects a signal voltage lower than the operating range of the sensor, this DTC sets.

DTC Descriptors

This diagnostic procedure supports the following DTC:

DTC P0462 Fuel Level Sensor Circuit Low Voltage

Conditions for Running the DTC

* The engine is operating.
* DTC P0462 runs continuously once the above conditions are met.

Conditions for Setting the DTC

* The ECM detects that fuel level signal voltage is less than 0.20 volts.
* The above condition is present for more than 10 seconds.

Action Taken When the DTC Sets

* The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
* The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
* The fuel gage defaults to empty.

Conditions for Clearing the MIL/DTC

* The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
* A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
* A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
* Clear the MIL and the DTC with a scan tool.

Test Description

The number below refers to the step number on the diagnostic table.
2. This step verifies that a condition exists.
4. This step tests for a condition in the 5-volt reference circuit of the fuel level sensor. If the DMM does not display more than the specified voltage, test for a short to ground or an open in the 5-volt reference circuit.
5. This step tests for a condition in the signal circuit of the fuel level sensor. If the Fuel Level Voltage parameter does not display more than the specified voltage, test for a short to ground or an open in the signal circuit.