2004 Infiniti QX56 AWDFACTORY OEM SERVICE PROCEDURE

Diagnostic Procedure

  1. CHECK DTC WITH COMBINATION METER 

    Refer to COMBINATION METERS .

    OK or NG

    OK: GO TO 2.

    NG: GO to FUEL LEVEL SENSOR UNIT .

  2. CHECK GROUND CONNECTIONS 
    1. Turn ignition switch OFF.
    2. Loosen and retighten ground three screws on the body.
      Fig 1: Locating Body Ground
      G02691337Courtesy of NISSAN MOTOR CO., U.S.A.

      Refer to GROUND INSPECTION .

    OK or NG

    OK: GO TO 3.

    NG: Repair or replace ground connections.

  3. CHECK FUEL TANK TEMPERATURE SENSOR POWER SUPPLY CIRCUIT 
    1. Disconnect "fuel level sensor unit and fuel pump" harness connector.
    2. Turn ignition switch ON.
      Fig 2: Locating Fuel Level Sensor Unit And Fuel Pump Harness Connector
      G02691338Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Check voltage between "fuel level sensor unit and fuel pump" terminal 4 and ground with CONSULT-II or tester.

      Voltage: Approximately 5V 

      Fig 3: Checking Voltage Between Fuel Level Sensor Unit, Fuel Pump Terminal 4 & Ground
      G02691339Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG

    OK: GO TO  5.

    NG: GO TO 4.

  4. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors C1, E41
    • Harness for open or short between ECM and "fuel level sensor unit and fuel pump"

      : Repair harness or connector.

  5. CHECK FUEL TANK TEMPERATURE SENSOR GROUND CIRCUIT FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect combination meter harness connector.
    3. Check harness continuity between "fuel level sensor unit and fuel pump" terminal 5 and combination meter terminal 16. Refer to Wiring Diagram.

      Continuity should exist. 

    4. Also check harness for short to ground and short to power.

    OK or NG

    OK: GO TO  7.

    NG: GO TO 6.

  6. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors C1, E41
    • Harness connectors E152, M31
    • Harness for open or short between "fuel level sensor unit and fuel pump" and combination meter

      : Repair open circuit or short to ground or short to power in harness or connector.

  7. CHECK FUEL TANK TEMPERATURE SENSOR 

    Refer to COMPONENT INSPECTION .

    OK or NG

    OK: GO TO 8.

    NG: Replace fuel level sensor unit.

  8. CHECK INTERMITTENT INCIDENT 

    Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .

    : INSPECTION END 

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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