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Home >> Infiniti >> 2005 >> QX56 AWD >> Repair and Diagnosis >> Engine Performance >> Engine Control System >> DTC P1122: Electric Throttle Control Function >> 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
      G02389019Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK: GO TO 2.
    2. NG: Repair or replace ground connections.
  2. CHECK THROTTLE CONTROL MOTOR RELAY INPUT SIGNAL CIRCUIT-I 
    1. Check voltage between ECM terminal 3 and ground under the following conditions with CONSULT-II or tester.
      VOLTAGE CONDITION SPECIFICATION

      Ignition switch Voltage
      OFF Approximately 0V
      ON Battery voltage (11 - 14V)

    OK or NG 

    1. OK: GO TO  9.
    2. NG: GO TO 3.
    Fig 2: Checking Voltage Between ECM Terminal 3 & Ground
    G02389020Courtesy of NISSAN MOTOR CO., U.S.A.
  3. CHECK THROTTLE CONTROL MOTOR RELAY POWER SUPPLY CIRCUIT-I 
    1. Turn ignition switch OFF.
    2. Check voltage between ECM terminal 104 and ground with CONSULT-II or tester.
      1. Voltage: Battery voltage 

    OK or NG 

    1. OK: GO TO  6.
    2. NG: GO TO 4.
    Fig 3: Checking Voltage Between ECM Terminal 104 & Ground
    G02389021Courtesy of NISSAN MOTOR CO., U.S.A.
  4. CHECK THROTTLE CONTROL MOTOR RELAY POWER SUPPLY CIRCUIT-II 
    1. Disconnect ECM harness connector.
    2. Disconnect IPDM E/R harness connector E122.
    3. Check harness continuity between ECM terminal 104 and IPDM E/R terminal 47. 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 5.
    2. NG: Repair open circuit or short to ground or short to power in harness or connectors.
  5. CHECK FUSE 
    1. Disconnect 20A fuse.
    2. Check 20A fuse for blown.

    OK or NG 

    1. OK: GO TO  8.
    2. NG: Replace 20A fuse.
  6. CHECK THROTTLE CONTROL MOTOR RELAY INPUT SIGNAL CIRCUIT-II 
    1. Disconnect ECM harness connector.
    2. Disconnect IPDM E/R harness connector E119.
    3. Check harness continuity between ECM terminal 3 and IPDM E/R terminal 6. 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: GO TO 7.
  7. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors E2, F32
    • Harness for open or short between ECM and IPDM E/R
      1. Repair open circuit or short to ground or short to power in harness or connectors.
  8. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    OK or NG 

    1. OK: Replace IPDM E/R. Refer to "IPDM E/R (INTELLIGENT POWER DISTRIBUTION MODULE ENGINE ROOM) ".
    2. NG: Repair or replace harness or connectors.
  9. CHECK THROTTLE CONTROL MOTOR OUTPUT SIGNAL CIRCUIT FOR OPEN OR SHORT 
    1. Turn ignition switch OFF.
    2. Disconnect electric throttle control actuator harness connector.
    3. Disconnect ECM harness connector.
    4. Check harness continuity between the following terminals. Refer to WIRING DIAGRAM .
      Fig 4: Throttle Control Motor Output Signal Circuit Continuity Table
      G02389022Courtesy of NISSAN MOTOR CO., U.S.A.
    5. Also check harness for short to ground and short to power.

    OK or NG 

    1. OK: GO TO 10.
    2. NG: Repair or replace.
    Fig 5: Locating Throttle Position Sensor & Throttle Control Motor Harness Connector
    G02389023Courtesy of NISSAN MOTOR CO., U.S.A.
  10. CHECK ELECTRIC THROTTLE CONTROL ACTUATOR VISUALLY 
    1. Remove the intake air duct.
    2. Check if foreign matter is caught between the throttle valve and the housing.

    OK or NG 

    1. OK: GO TO 11.
    2. NG: Remove the foreign matter and clean the electric throttle control actuator inside.
    Fig 6: Locating Electric Throttle Control Actuator
    G02389024Courtesy of NISSAN MOTOR CO., U.S.A.
  11. CHECK THROTTLE CONTROL MOTOR 

    Refer to "COMPONENT INSPECTION "

    OK or NG 

    1. OK: GO TO 12.
    2. NG: GO TO  13.
  12. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT "

    OK or NG 

    1. OK: GO TO 13.
    2. NG: Repair or replace harness or connectors.
  13. 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