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Home >> Infiniti >> 2007 >> QX56 RWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - DTCS P0451 To P1217 >> DTC P0550 PSP Sensor >> Diagnostic Procedure
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Diagnostic Procedure

  1. CHECK GROUND CONNECTIONS 
    1. Turn ignition switch OFF.
    2. Loosen and retighten three ground screws on the body.

      Refer to "GROUND INSPECTION ".

      Fig 1: Checking Ground Connections
      G04900129Courtesy of NISSAN NORTH AMERICA, INC.

    OK or NG 

    OK: GO TO 2.

    NG: Repair or replace ground connections.

  2. CHECK PSP SENSOR POWER SUPPLY CIRCUIT 
    1. Disconnect power steering pressure (PSP) sensor (1) harness connector.
    2. Turn ignition switch ON.
      Fig 2: Identifying Power Steering Pressure Sensor (1) Harness Connector
      G04900561Courtesy of NISSAN NORTH AMERICA, INC.
    3. Check voltage between PSP sensor terminal 1 and ground with CONSULT-II or tester.

      Voltage: Approximately 5V 

      Fig 3: Checking Voltage Between PSP Sensor Terminal 1 And Ground
      G04875300Courtesy of NISSAN NORTH AMERICA, INC.

    OK or NG 

    OK: GO TO 3.

    NG: Repair harness or connectors.

  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 and 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