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Home >> Infiniti >> 2008 >> QX56 AWD >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Engine Control System - DTCS P1148 To P2A03 >> DTC P2138: App Sensor >> 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
      G05739691Courtesy 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
      G05739692Courtesy 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 3.

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

    Fig 3: Checking Voltage Between APP Sensor Terminal 2 And Ground
    G05739693Courtesy of NISSAN MOTOR CO., U.S.A.
  3. CHECK APP SENSOR 2 POWER SUPPLY CIRCUIT-I
    1. Turn ignition switch ON.
    2. Check voltage between APP sensor terminal 6 and ground with CONSULT-III or tester.

      Voltage: Approximately 5V 

    OK or NG 

    OK: GO TO  8.

    NG: GO TO 4.

    Fig 4: Checking Voltage Between APP Sensor Terminal 1 And Ground
    G05739694Courtesy of NISSAN MOTOR CO., U.S.A.
  4. CHECK APP SENSOR 2 POWER SUPPLY CIRCUIT-II
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between APP sensor terminal 6 and ECM terminal 91.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

    OK or NG 

    OK: GO TO 5.

    NG: Repair open circuit in harness or connectors.

  5. CHECK APP SENSOR 2 POWER SUPPLY CIRCUIT-III

    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
    47 Electric throttle control actuator terminal 2 "WIRING DIAGRAM - ENGINE CONTROL SYSTEM - "
    91 APP sensor terminal 6

    OK or NG 

    OK: GO TO 6.

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

  6. CHECK THROTTLE POSITION SENSOR

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    OK: GO TO  12.

    NG: GO TO 7.

  7. REPLACE ELECTRIC THROTTLE CONTROL ACTUATOR
    1. Replace the electric throttle control actuator.
    2. Perform "THROTTLE VALVE CLOSED POSITION LEARNING ".
    3. Perform "IDLE AIR VOLUME LEARNING ".

      INSPECTION END 

  8. CHECK APP SENSOR GROUND CIRCUIT FOR OPEN AND SHORT
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between ECM terminal 82 and APP sensor terminal 1, ECM terminal 83 and APP sensor terminal 3.

      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 9.

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

  9. CHECK APP SENSOR INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT
    1. Check harness continuity between ECM terminal 106 and APP sensor terminal 2, ECM terminal 98 and APP sensor terminal 5.

      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 10.

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

  10. CHECK ACCELERATOR PEDAL POSITION SENSOR

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    OK: GO TO  12.

    NG: GO TO 11.

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

      INSPECTION END 

  12. CHECK INTERMITTENT INCIDENT

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

    INSPECTION END