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
      G02691470Courtesy 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 CONNECTOR 
    1. Disconnect EVAP control system pressure sensor harness connector.
      Fig 2: Locating EVAP Control System Pressure Sensor & EVAP Canister Vent Control Valve
      G02691471Courtesy of NISSAN MOTOR CO., U.S.A.
    2. Check sensor harness connector for water.

    Water should not exist. 

    OK or NG

    OK: GO TO 3.

    NG: Repair or replace harness connector.

  3. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR POWER SUPPLY CIRCUIT 
    1. Turn ignition switch ON.
    2. Check voltage between EVAP control system pressure sensor terminal 3 and ground with CONSULT-II or tester.

      Voltage: Approximately 5V 

    OK or NG

    OK: GO TO  5.

    NG: GO TO 4.

    Fig 3: Checking Voltage Between EVAP Control System Pressure Sensor Terminal 3 & Ground
    G02691472Courtesy of NISSAN MOTOR CO., U.S.A.
  4. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors C1, E41
    • Harness connectors E5, F14
    • Harness for open or short between EVAP control system pressure sensor and ECM

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

  5. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR GROUND CIRCUIT FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between EVAP control system pressure sensor terminal 1 and ECM terminal 67.

      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 E5, F14
    • Harness for open or short between EVAP control system pressure sensor and ECM

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

  7. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT 
    1. Check harness continuity between ECM terminal 32 and EVAP control system pressure sensor terminal 2.

      Refer to Wiring Diagram.

      Continuity should exist. 

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

    OK or NG

    OK: GO TO  9.

    NG: GO TO 8.

  8. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors C1, E41
    • Harness connectors E5, F14
    • Harness for open or short between EVAP control system pressure sensor and ECM

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

  9. CHECK EVAP CONTROL SYSTEM PRESSURE SENSOR 

    Refer to COMPONENT INSPECTION .

    OK or NG

    OK: GO TO 10.

    NG: Replace EVAP control system pressure sensor.

  10. 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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