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Home >> Jeep >> 2021 >> Grand Cherokee Trackhawk >> Repair and Diagnosis >> Engine Performance >> System >> 6.2L - DTCS P0443 To P0688 >> DTC Troubleshooting >> P0461-Fuel Level Sensor 1 Performance >> Diagnostic Test
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Diagnostic Test

  1. CHECK FOR FUEL LEVEL SENSOR CIRCUIT DTCS 
    NOTE:

    Diagnose and repair any CAN BUS, communication or implausible signal DTCs before proceeding with this test.

    NOTE:

    Excessive pressure build up or vacuum in the Evaporative system could possibly contribute to this DTC being set. Diagnose and repair any Evaporative System DTCs before continuing with this fault.

    1. Turn the ignition on.
    2. With the scan tool, read and record DTCs on the repair order.

      Are any Fuel Level Sensor Circuit DTCs present?

      Yes 

      • Diagnose the appropriate Fuel Level Sensor Circuit DTCs before continuing.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  2
  2. VISUALLY INSPECT FUEL TANK 
    1. Turn the ignition off.
    2. Visually inspect the Fuel Tank for any obvious physical damage that may restrict the Fuel Sending Unit float from moving.

      Is the Fuel Tank damaged?

      Yes 

      • Replace the Fuel Tank in accordance with the Service Information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  3
  3. EMPTY FUEL TANK AND CHECK THE FUEL LEVEL SENSOR READINGS 
    WARNING:

    The fuel system is under a constant pressure (even with the engine off). Before testing or servicing any fuel system hose, fitting or line, the fuel system pressure must be released. Failure to follow these instructions can result in possible serious or fatal injury.

    1. Disconnect the fuel supply line at the fuel rail.
    2. Connect a drain hose between the fuel supply line and an approved fuel container.
    3. Turn the ignition on.
    4. Remove the Fuel Pump Relay from the PDC.
    5. Connect a jumper across terminal 30 and terminal 87 of the Fuel Pump Relay connector to actuate the Fuel Pump Assembly until all fuel is removed from the Fuel Tank.
    6. Remove the jumper when there is no more fuel coming out of the hose.
      NOTE:

      If the Fuel Tank is completely empty, both Fuel Level Sensors should read at or near empty (indicated by a voltage reading of approximately 4.3-4.5 volts).

    7. With the scan tool, read the voltage for Fuel Level Sensor 1 and Fuel Level Sensor 2.

      Are both Fuel Level Sensors reading at or near empty?

      Yes 

      • Go To  4

      No, Fuel Level Sensor 1 is not reading empty 

      • Go To  5

      No, Fuel Level Sensor 2 is not reading empty 

      • Go To  6
  4. REFILL FUEL TANK AND CHECK THE FUEL LEVEL SENSOR READINGS 
    NOTE:

    Make sure that you have enough fuel to put into the vehicle to overflow into the secondary tank. It may be necessary to add more fuel to what was removed to do so.

    1. While monitoring the Fuel Level Sensor voltage readings on scan tool, begin putting fuel back into the Fuel Tank.
    2. With the scan tool, read the voltages for Fuel Level Sensor 1 and Fuel Level Sensor 2.
      NOTE:

      The Primary Fuel Level Sensor voltage should decrease at a steady rate as fuel is added until it reaches near full. As fuel starts to overflow to the secondary tank, the Secondary Fuel Level Sensor voltage should also start to decrease at a steady rate.

      Does the voltage for both Fuel Level Sensors change smoothly without any pause while fuel was added?

      Yes 

      • Go To  6

      No, Fuel Level Sensor 2 voltage does not decrease correctly 

      • Go To  6

      No, Fuel Level Sensor 1 voltage does not decrease correctly 

      • Go To  5
  5. INTERNAL INSPECTION OF THE PRIMARY FUEL TANK 
    1. Remove or lower the Fuel Tank in accordance with the Service Information. Refer to TANK, FUEL, REMOVAL .
    2. Remove the Primary Fuel Pump Module.
    3. Visually inspect the inside of the Fuel Tank for any obstructions or deformities.
    4. Inspect the Primary Fuel Level Sensor Float arm for damage.

      Were any problems found?

      Yes 

      No 

      • Replace the Primary Fuel Level Sensor in accordance with the service information.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
  6. INTERNAL INSPECTION OF THE SECONDARY FUEL TANK 
    1. Remove or lower the Fuel Tank in accordance with the Service Information. Refer to TANK, FUEL, REMOVAL .
    2. Remove the Secondary Fuel Pump Module. Refer to MODULE, FUEL PUMP, REMOVAL .
    3. Visually inspect the Siphon Tube for any obstructions, cracks or loose connections.
    4. Inspect the Secondary Fuel Level Sensor for damage.

      Were any problems found?

      Yes 

      • Replace the Secondary Fuel Level Sensor and/or Siphon Pump Assembly in accordance with the service information.
        NOTE:

        If the Siphon Pump Assembly or Siphon Tube are at fault, check the fuel and Fuel Tank for dirt or contamination. Even a small amount of dirt in the fuel can damage a Siphon Pump or Tube.

      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .

      No 

      • Go To  7
  7. CHECK RELATED HARNESS CONNECTIONS 
    1. Disconnect all PCM harness connectors.
    2. Disconnect all related in-line harness connections (if equipped).
    3. Disconnect the related component harness connectors.
    4. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
      • Proper connector installation.
      • Damaged connector locks.
      • Corrosion.
      • Other signs of water intrusion.
      • Weather seal damage (if equipped).
      • Bent terminals.
      • Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
      • Terminals that have been pushed back into the connector cavity.
      • Check for spread terminals and verify proper terminal tension.

      Repair any conditions that are found.

    5. Connect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
    6. Connect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
    7. Connect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
    8. With the scan tool, erase DTCs.
    9. Test drive or operate the vehicle in accordance with the when monitored and set conditions.
    10. With the scan tool, read DTCs.

      Did the DTC return?

      Yes 

      No 

      • The wiring or poor connection problem has been repaired.
      • Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
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