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Home >> Infiniti >> 2010 >> QX56 AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - DTCS P0327 To P0850 >> DTC P0643: Sensor Power Supply >> Diagnosis Procedure

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 Ground Screws On Body
      G06315710Courtesy 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: Identifying Accelerator Pedal Position (APP) Sensor
      G06315711Courtesy 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 7 And Ground
      G06315712Courtesy 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

    CONNECTOR TERMINALS 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.

  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