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Home >> Infiniti >> 2008 >> QX56 AWD >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Engine Control System - DTCS P0327 To P1145 >> DTC P0643: Sensor Power Supply >> Diagnosis Procedure
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Diagnosis 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: Identifying Body Ground Screw
      G05739587Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    OK: GO TO 2.

    NG: Repair or replace ground connections.

  2. CHECK APP SENSOR 1 POWER SUPPLY CIRCUIT
    1. Disconnect accelerator pedal position (APP) sensor harness connector.
    2. Turn ignition switch ON.
      Fig 2: Checking APP Sensor 1 Power Supply Circuit
      G05739588Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Check voltage between APP sensor terminal 7 and ground with CONSULT-III or tester.

      Voltage: Approximately 5V 

    OK or NG 

    OK: GO TO  5.

    NG: GO TO 3.

    Fig 3: Checking Voltage Between APP Sensor Terminal 2 And Ground
    G05739589Courtesy of NISSAN MOTOR CO., U.S.A.
  3. CHECK SENSOR POWER SUPPLY CIRCUITS

    Check harness for short to power and short to ground, between the following terminals

    ECM TERMINAL REFERENCE CHART

    ECM terminal Sensor terminal Reference Wiring Diagram
    48 EVAP control system pressure sensor terminal 3 "WIRING DIAGRAM - ENGINE CONTROL SYSTEM - "
    49 Refrigerant pressure sensor terminal 1
    Battery current sensor terminal 1
    68 Power steering pressure sensor terminal 1
    90 APP sensor terminal 7

    OK or NG 

    OK: GO TO 4.

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

  4. CHECK COMPONENTS

    Check the following.

    OK or NG 

    OK: GO TO  7.

    NG: Replace malfunctioning components.

  5. CHECK ACCELERATOR PEDAL POSITION SENSOR

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    OK: GO TO  7.

    NG: GO TO 6.

  6. REPLACE ACCELERATOR PEDAL ASSEMBLY
    1. Replace accelerator pedal position assembly.
    2. Perform "ACCELERATOR PEDAL RELEASED POSITION LEARNING ".
    3. Perform "THROTTLE VALVE CLOSED POSITION LEARNING ".
    4. Perform "IDLE AIR VOLUME LEARNING ".

      INSPECTION END 

  7. CHECK INTERMITTENT INCIDENT

    Refer to "HOW TO CHECK TERMINAL " and "INTERMITTENT INCIDENT ".

    INSPECTION END