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
      G02691534Courtesy 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 PSP SENSOR POWER SUPPLY CIRCUIT 
    1. Disconnect PSP sensor harness connector.
    2. Turn ignition switch ON.
      Fig 2: Disconnecting Power Steering Pressure Sensor Harness Connector
      G02691535Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Check voltage between PSP sensor terminal 1 and ground with CONSULT-II or tester.

      Voltage: Approximately 5V 

    OK or NG

    OK: GO TO 3.

    NG: Repair harness

    Fig 3: Checking Voltage Between PSP Sensor Terminal 1 & Ground With CONSULT-II
    G02691536Courtesy of NISSAN MOTOR CO., U.S.A.
  3. CHECK PSP SENSOR GROUND CIRCUIT FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between PSP sensor terminal 3 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 4.

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

  4. CHECK PSP SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT 
    1. Check harness continuity between ECM terminal 12 and PSP sensor terminal 2.

      Continuity should exist. 

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

    OK or NG

    OK: GO TO 5.

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

  5. CHECK PSP SENSOR 

    Refer to COMPONENT INSPECTION .

    OK or NG

    OK: GO TO 6.

    NG: Replace PSP sensor.

  6. 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.

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