2004 Infiniti QX56 AWDFACTORY OEM SERVICE PROCEDURE

Diagnostic Procedure

  1. CHECK GROUND CONNECTIONS 
    1. Turn ignition switch OFF.
    2. Loosen and retighten ground three screws on the body.
      Fig 1: Locating Body Ground
      G02691241Courtesy of NISSAN MOTOR CO., U.S.A.

    Refer to GROUND INSPECTION .

    OK or NG

    OK: GO TO 2.

    NG: Repair or replace ground connections.

  2. CHECK ECT SENSOR POWER SUPPLY CIRCUIT 
    1. Disconnect engine coolant temperature (ECT) sensor harness connector.
      Fig 2: Locating Engine Coolant Temperature Sensor
      G02691242Courtesy of NISSAN MOTOR CO., U.S.A.
    2. Turn ignition switch ON.
    3. Check voltage between ECT sensor terminal 1 and ground with CONSULT-II or tester.

      Voltage: Approximately 5V 

    OK or NG

    OK: GO TO  4.

    NG: GO TO 3.

    Fig 3: Checking Voltage Between ECT Sensor Terminal 1 & Ground
    G02691243Courtesy of NISSAN MOTOR CO., U.S.A.
  3. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connector F26, F101
    • Harness for open or short between ECM and engine coolant temperature sensor

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

  4. CHECK ECT SENSOR GROUND CIRCUIT FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between ECT sensor terminal 2 and ECM terminal 67.

      Refer to Wiring Diagram.

      Continuity should exist. 

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

    OK or NG

    OK: GO TO  6.

    NG: GO TO 5.

  5. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connector F26, F101
    • Harness for open and short between ECT sensor and ECM

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

  6. CHECK ENGINE COOLANT TEMPERATURE SENSOR 

    Refer to  COMPONENT INSPECTION   .

    OK or NG

    OK: GO TO 7.

    NG: Replace engine coolant temperature sensor.

  7. CHECK INTERMITTENT INCIDENT 

    Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .

    : INSPECTION END 

Factory Service Tools

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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.