GM Service Manual Online
For 1990-2009 cars only

DTC P0463 Sedan

Circuit Description

The fuel level sensor changes resistance based on fuel level. The powertrain control module (PCM) monitors the signal circuit of the fuel level sensor in order to determine fuel level. When the fuel tank is full, the sensor resistance is high and the PCM senses a high signal voltage. When the fuel tank is empty, the sensor resistance is low and the PCM senses a low signal voltage. The PCM uses the signal circuit of the fuel level sensor in order to calculate the total remaining fuel in the tank. The PCM sends the fuel level percent via the GMLAN serial data circuit 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.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0463 Fuel Level Sensor Circuit High Voltage

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

    • The fuel level signal is greater than 3 volts or 98 percent.
    • The above condition is present for greater than 10 seconds.

Action Taken When the DTC Sets

    • The fuel gage defaults to empty.
    • The low fuel indicator illuminates.
    • The PCM records the operating conditions at the time the diagnostic fails. The 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 PCM receives the clear code command from the scan tool.

Diagnostic Aids

    • Use the Freeze Frame and/or Failure Records data in order to locate an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data may aid in determining the number of miles since the DTC set. The Fail Counter and Pass Counter can also aid in determining the number of ignition cycles that the diagnostic reported a pass and/or fail. Operate the vehicle within the same freeze frame conditions, i.e. RPM, load, vehicle speed, temperature, etc. This will isolate when the DTC failed.
    • Refer to Testing for Intermittent Conditions and Poor Connections .

Test Description

The number below refers to the step number on the diagnostic table.

  1. Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.

Step

Action

Value(s)

Yes

No

Schematic Reference: Instrument Cluster Schematics

Connector End View Reference: Powertrain Control Module Connector End Views for the 2.2L engine or Powertrain Control Module Connector End Views for the 3.5L engine

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, observe the Fuel Tank Level Remaining parameter in the powertrain control module (PCM) evaporative emission (EVAP) Data list.

Does the scan tool indicate that the Fuel Tank Level Remaining parameter is greater than the specified value?

98%

Go to Step 3

Go to Diagnostic Aids

3

  1. Turn OFF the ignition.
  2. Disconnect C413.
  3. 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.
  4. Turn the ignition ON, with the engine OFF.
  5. With a scan tool, observe the Fuel Tank Level Remaining parameter.

Does the scan tool indicate that the Fuel Tank Level Remaining parameter is less than the specified value?

3%

Go to Step 6

Go to Step 4

4

Test the signal circuit of the fuel level sensor for the following:

    • An open
    • A high resistance
    • A short to voltage

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 5

5

Test the low reference circuit of the fuel level sensor for an open or for a high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 9

6

Test the signal circuit of the fuel level sensor for the following between C413 and the fuel level sensor.

    • An open
    • A high resistance
    • A short to voltage

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 7

7

Test the low reference circuit of the fuel level sensor for an open, or for a high resistance between C413 and the fuel level sensor. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 8

8

Inspect for poor connections at the harness connector of the fuel level sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 10

9

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

10

Replace the fuel level sensor. Refer to the following:

    •  Fuel Level Sensor Replacement for the 2.2L engine
    •  Fuel Level Sensor Replacement for the 3.5L engine

Did you complete the replacement?

--

Go to Step 12

--

11

Replace the PCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 12

--

12

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK

DTC P0463 Extended Sedan

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.

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Fuel Level Sensor Reference Voltage Circuit

P0462

--

--

P0461

Fuel Level Sensor Signal Circuit

P0462

P0463

1

P0463

P0461

Fuel Level Sensor Low Reference Circuit

--

P0463

1

P0463

P0461

1. Fuel Gage Inaccurate or Inoperative

Circuit/System Description

The fuel level sensor changes resistance in response to the fuel level. The 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 PCM senses a low signal voltage. When the fuel tank is empty, the sensor resistance is high and the PCM senses a high signal voltage. The PCM uses the signal circuit of the fuel level sensor in order to calculate the percentage of remaining fuel in the tank. The PCM sends the fuel level percentage via GMLAN serial data circuit 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 sensor output is greater than 3.0 volts.
    • The above condition is present for greater than 10 seconds.

Action Taken When the DTC Sets

    • The fuel gage defaults to empty.
    • The low fuel indicator illuminates.
    • The PCM records the operating conditions at the time that the diagnostic test fails. The 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 PCM receives a clear code command from the scan tool.

Reference Information

Fuel Level Specifications

Fuel Level Specifications

Schematic Reference

    •  Instrument Cluster Schematics
    •  Emission Hose Routing Diagram for the 2.2L engine
    •  Engine Controls Schematics for the 3.5L engine

Connector End View Reference

    •  Instrument Panel, Gages, and Console Connector End Views
    •  Powertrain Control Module Connector End Views for the 2.2L engine
    •  Powertrain Control Module Connector End Views for the 3.5L engine

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Scan Tool Data List

Circuit/System Verification

With the scan tool installed and the ignition ON, the Fuel Tank Level Remaining parameter in the PCM EVAP Data List indicates a value at or greater than 4 percent.

Circuit/System Testing

  1. With the ignition OFF, disconnect C413.
  2. Connect a 3-ampere 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 PCM EVAP Data List.
  4. 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 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 C413 and the fuel level sensor.
    If both the signal circuit and the low reference circuit tests normal between C413 and the fuel level sensor, replace the fuel level sensor.

Repair Instructions

    •  Fuel Level Sensor Replacement for the 2.2L engine
    •  Fuel Sender Assembly Replacement for the 3.5L engine
    •  Control Module References for the PCM replacement, setup, and programming