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Home >> Infiniti >> 2005 >> QX56 AWD >> Repair and Diagnosis >> Engine Performance >> Engine Control System >> DTC P2127, P2128: App 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
      G02389360Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO 2.
    2. NG: Repair or replace ground connections.
  2. CHECK APP SENSOR 2 POWER SUPPLY CIRCUIT-I 
    1. Disconnect accelerator pedal position (APP) sensor harness connector.
    2. Turn ignition switch ON.
      Fig 2: Locating Accelerator Pedal Position Sensor
      G02389361Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Check voltage between APP sensor terminal 6 and ground with CONSULT-II or tester.
      1. Voltage: Approximately 5V 

    OK or NG 

    1. OK: GO TO  7.
    2. NG: GO TO 3.
    Fig 3: Checking Voltage Between APP Sensor Terminal 6 & Ground
    G02389362Courtesy of NISSAN MOTOR CO., U.S.A.
  3. 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 .
      1. Continuity should exist. 

    OK or NG 

    1. OK: GO TO 4.
    2. NG: Repair or replace open circuit.
  4. CHECK APP SENSOR 2 POWER SUPPLY CIRCUIT-III 

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

    ECM TERMINALS REFERENCE

    ECM terminal Sensor terminal Reference Wiring Diagram
    47 Electric throttle control actuator terminal 2 WIRING DIAGRAM 
    91 APP sensor terminal 6 WIRING DIAGRAM 

    OK or NG 

    1. OK: GO TO 5.
    2. NG: Repair short to ground or short to power in harness or connectors.
  5. CHECK THROTTLE POSITION SENSOR 

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    1. OK: GO TO  11.
    2. NG: GO TO 6.
  6. 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 ".
      1. : INSPECTION END 
  7. CHECK APP SENSOR 2 GROUND CIRCUIT FOR OPEN AND SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Check harness continuity between ECM terminal 83 and APP sensor terminal 3. Refer to WIRING DIAGRAM .
      1. Continuity should exist. 
    4. Also check harness for short to ground and short to power.

    OK or NG 

    1. OK: GO TO 8.
    2. NG: Repair open circuit or short to ground or short to power in harness or connectors.
  8. CHECK APP SENSOR 2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT 
    1. Check harness continuity between ECM terminal 98 and APP sensor terminal 5. Refer to WIRING DIAGRAM .
      1. Continuity should exist. 
    2. Also check harness for short to ground and short to power.

    OK or NG 

    1. OK: GO TO 9.
    2. NG: Repair open circuit or short to ground or short to power in harness or connectors.
  9. CHECK APP SENSOR 

    Refer to "COMPONENT INSPECTION ".

    OK or NG 

    1. OK: GO TO  11.
    2. NG: GO TO 10.
  10. 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 ".
      1. : INSPECTION END 
  11. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    1. INSPECTION END