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DTC P0461 Fuel Level Sensor Performance Single Tank


Object Number: 600797  Size: SF
Engine Controls Components
OBD II Symbol Description Notice
VCM Connector End Views
Engine Data Sensors-MAP, IAT, ECT, and TP
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The vehicle control module (VCM) requires an accurate indication of fuel level for evaporative emission (EVAP) system diagnosis. The fuel level in the fuel tank changes the rate of vacuum decay for the EVAP system leak diagnostic trouble codes (DTCs).

The fuel level sensor changes resistance based on fuel level. The fuel level sensor has a signal circuit and a ground circuit. The VCM applies a voltage of approximately 5 volts on the signal circuit to the sensor. The VCM monitors changes in this voltage caused by changes in the resistance of the sensor in order to determine the fuel level.

When the fuel tank is full, the sensor resistance is high, and the signal voltage of the VCM is only pulled down a small amount through the sensor to ground. Therefore, the VCM will sense a high signal voltage, indicating a full fuel tank. When the fuel tank is empty, the sensor resistance is low, and the signal voltage is pulled down a greater amount. This causes the VCM to sense a low signal voltage, indicating an empty fuel tank.

The VCM uses the input from the fuel level sensor in order to calculate the fuel level in the fuel tank. This information is then sent to the instrument panel cluster (IPC) through serial data.

The diagnostic will not run when the tank is more than 85 percent full or less than 15 percent full. This sensor signal disables the misfire when the fuel levels are less than 15 percent.

Conditions for Running the DTC

The VCM has confirmed that the fuel tank is between 15 percent and 85 percent full.

Conditions for Setting the DTC

The VCM does not detect a decrease in fuel level over a distance of 200 miles (320 Km).

Action Taken When the DTC Sets

    • The control module stores the DTC in history after the first failure but will not illuminate the malfunction indicator lamp (MIL).
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores the failure information in the scan tools Freeze Frame/Failure Records.

Conditions for Clearing the MIL/DTC

    • A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles.
    • A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant temperature exceeds 70°C (160°F) during the same ignition cycle.
    • Use the scan tool Clear Information function.

Diagnostic Aids

Important: The fuel level is used to determine EVAP system diagnosis. Always diagnose the fuel level sensor before any other EVAP system components or DTCs.

Do not use the fuel gauge as an indication of a shorted or open circuit because the IPC may always default to EMPTY or FULL depending upon the vehicle model.

Check for the following conditions:

    • A poor connection or damaged harness -- Inspect the VCM harness connectors for the following:
       - Backed out terminals
       - Improper mating
       - Broken locks
       - Poor wire to terminal connections
    • Intermittent test -- Monitor a scan tool or a digital voltmeter connected between the related circuits while moving the connectors and harnesses. If the failure is induced, the voltage reading will change. This will help locate a circuit problem.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step determines if there is a wiring problem.

  2. This step determines if the fuel level sensor signal and ground circuits are OK.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Important: : If DTCs P0462 and P0463 are also set, diagnose these codes first.

  1. Turn OFF the ignition.
  2. Disconnect the fuel level sensor electrical connector at the fuel tank.
  3. Turn ON the ignition, leaving the engine OFF.
  4. Monitor the fuel level sensor voltage using the scan tool.

Is the fuel level voltage near the specified value?

5.0 V

Go to Step 3

Go to Step 4

3

  1. Jumper the fuel level sensor signal and ground circuits together.
  2. Monitor the fuel level sensor voltage using the scan tool.

Is the fuel level sensor voltage near the specified value?

0.0 V

Go to Step 5

Go to Step 6

4

Repair the open or short to ground in the fuel level signal circuit.

Is the action complete?

--

Go to Step 11

Go to Step 9

5

Check the fuel level sender for the following:

    • Proper alignment in the fuel tank
    • A restricted or binding fuel level float

Repair as necessary.

Was a problem found?

--

Go to Step 11

Go to Step 8

6

Check the fuel level signal and ground circuits for an open.

Was a problem found?

--

Go to Step 7

Go to Step 9

7

Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 11

--

8

Replace the fuel level sensor. Refer to Fuel Level Sensor Replacement .

Is the action complete?

--

Go to Step 11

--

9

  1. Check the terminal contact at the VCM.
  2. Repair the terminal contact if needed. Refer to Connector Repairs in Wiring Systems.

Was terminal contact repaired?

--

Go to Step 11

Go to Step 10

10

Important: The replacement VCM must be programmed.

Replace the VCM. Refer to VCM Replacement/Programming .

Is the action complete?

--

Go to Step 11

--

11

  1. Using the scan tool, clear the DTCs.
  2. Start the engine.
  3. Select DTC and the Specific DTC function.
  4. Enter the DTC number which was set.
  5. Operate the vehicle, with the Conditions for Setting this DTC, until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate the diagnostic Passed?

--

Go to Step 12

Go to Step 2

12

Does the scan tool display any additional undiagnosed DTCs?

--

Go to the applicable DTC table

System OK

DTC P0461 Fuel Level Sensor Performance Dual Tanks


Object Number: 600794  Size: MF
Engine Controls Components
OBD II Symbol Description Notice
VCM Connector End Views
Fuel Pump Control-Single Tank
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The fuel level sensor is an important input to the vehicle control module (VCM) for the enhanced evaporative system diagnostic. The VCM needs the fuel level information in order to know the volume of fuel in the tank. The fuel level affects the rate of change in the air pressure in the evaporative emission (EVAP) system. Several of the enhanced evaporative system diagnostic sub-tests are dependent upon the correct fuel level information. The diagnostic will not run when the tank is more than 85 percent full or less than 15 percent full. This sensor signal disables the misfire when the fuel levels are less than 15 percent.

Conditions for Setting the DTC

    • The fuel tank level slosh test is completed.
    • The tank level main test is completed.
    • The fuel tank level data is valid.
    • The fuel level signal is unchanged over a distance of 200 miles.

Action Taken When the DTC Sets

    • The control module stores the DTC in history after the first failure but will not illuminate the malfunction indicator lamp (MIL).
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores the failure information in the scan tools Freeze Frame/Failure Records.

Conditions for Clearing the MIL or DTC

    • The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.
    • A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
    • Use a scan tool in order to clear the DTCs.

Diagnostic Aids

Check for the following conditions:

    • A poor connection or damaged harness -- Inspect VCM harness connectors for the following:
       - Backed out terminals
       - Improper mating
       - Broken locks
       - Poor wire-to-terminal connections
    • Intermittent test -- Monitor a scan tool or a digital voltmeter connected between the related circuits while moving the connectors and harnesses. If the failure is induced, the voltage reading will change. This will help locate a circuit problem.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step determines if sender is responding correctly.

  2. This step determines if the VCM is functioning correctly.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Install a scan tool.
  2. Record the fuel level sensor voltage.
  3. Change the level of the fuel in the primary fuel tank.

Did the fuel level sensor voltage change?

--

Go to Step 3

Go to Step 5

3

  1. Record the fuel level sensor voltage.
  2. Change the level of the fuel in the auxiliary fuel tank.

Did the fuel level sensor voltage change?

--

Go to Step 4

Go to Step 5

4

This DTC is intermittent.

Are any additional DTCs stored?

--

Go to the applicable DTC table

Go to Diagnostic Aids

5

  1. Turn OFF the ignition.
  2. Disconnect the fuel pump balance module electrical connector C2 (2 wire).
  3. Jumper the 5-volt circuit to the fuel level input circuit on the harness connector.
  4. Turn ON the ignition, leaving the engine OFF.
  5. Monitor the fuel level voltage parameter on the scan tool.

Is the voltage near the specified value?

5.0 V

Go to Step 9

Go to Step 6

6

  1. Remove the jumper.
  2. Measure the voltage on the 5-volt reference circuit at the fuel pump balance module using a DMM connected to ground

Is the voltage near the specified value?

5.0 V

Go to Step 7

Go to Step 13

7

Check the fuel level input circuit for an open, high resistance, or a short.

Did you find a problem?

--

Go to Step 13

Go to Step 8

8

Important: The replacement VCM must be programmed.

Replace the VCM. Refer to VCM Replacement/Programming .

Is the action complete?

--

Go to Step 17

--

9

Probe the ground circuit of the balance module C1 connector with a test lamp connected to B+.

Does the test lamp illuminate?

--

Go to Step 10

Go to Step 13

10

Probe the ignition positive voltage circuit of the fuel pump balance module connector C1 with a test lamp connected to ground.

Does the test lamp illuminate?

--

Go to Step 11

Go to Step 13

11

  1. Probe the primary fuel tank sender circuit with a DMM connected to ground.
  2. Record the measured resistance.
  3. Change the fuel level in the tank by at least 25 percent.

Does the resistance change by more than 20 ohms?

--

Go to Step 12

Go to Step 14

12

  1. Probe the auxiliary fuel tank sender circuit with a DMM connected to ground.
  2. Record the measured resistance.
  3. Change the fuel level in the tank by at least 25 percent.

Does the resistance change by more than 20 ohms?

--

Go to Step 16

Go to Step 14

13

Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 17

--

14

  1. Check the connections at the sender for corrosion. Make sure that connections are clean and tight.
  2. Repair the connections as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find a problem?

--

Go to Step 17

Go to Step 15

15

Replace the fuel level sensor. Refer to Fuel Sender Assembly Replacement .

Is the action complete?

--

Go to Step 17

--

16

Replace the fuel pump balance module.

Is the action complete?

--

Go to Step 17

--

17

  1. Use the scan tool in order to select the DTC and the Clear DTC Information functions.
  2. Start the engine.
  3. Allow the engine to idle until normal operating temperature is reached.
  4. Select DTC and the Specific DTC functions.
  5. Enter the DTC number which was set.
  6. Operate the vehicle, with the Conditions for Setting this DTC, until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate that the diagnostic Passed?

--

Go to Step 18

--

18

Does the scan tool display any additional undiagnosed DTCs?

--

Go to the applicable DTC table

System OK