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Home >> Infiniti >> 2004 >> QX56 RWD >> Repair and Diagnosis >> Engine Performance >> System >> 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 ground three screws on the body.
      Fig 1: Locating Body Ground
      G02691567Courtesy of NISSAN MOTOR CO., U.S.A.

      Refer to GROUND INSPECTION .

    OK or NG

    OK: GO TO 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.
      CHECKING VOLTAGE CONDITION

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

    OK or NG

    OK: GO TO  9.

    NG: GO TO 3.

    Fig 2: Checking Voltage Between ECM Terminal 3 & Ground
    G02691568Courtesy of NISSAN MOTOR CO., U.S.A.
  3. CHECK THROTTLE CONTROL MOTOR RELAY INPUT SIGNAL CIRCUIT-II 
    1. Turn ignition switch OFF.
    2. Disconnect ECM harness connector.
    3. Disconnect IPDM E/R harness connector E119.
    4. Check harness continuity between ECM terminal 3 and IPDM E/R terminal 6. Refer to Wiring Diagram.

      Continuity should exist. 

    5. Also check harness for short to ground and short to power.

    OK or NG

    OK: GO TO  5.

    NG: GO TO 4.

  4. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors E2, F32
    • Harness for open or short between ECM and IPDM E/R

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

  5. CHECK THROTTLE CONTROL MOTOR RELAY POWER SUPPLY CIRCUIT-I 
    1. Reconnect all harness connectors disconnected.
    2. Turn ignition switch OFF.
    3. Check voltage between ECM terminal 104 and ground with CONSULT-II or tester.

      Voltage: Battery voltage 

    OK or NG

    OK: GO TO  8.

    NG: GO TO 6.

    Fig 3: Checking Voltage Between ECM Terminal 104 & Ground
    G02691569Courtesy of NISSAN MOTOR CO., U.S.A.
  6. 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.

      Continuity should exist. 

    4. Also check harness for short to ground and short to power.

    OK or NG

    OK: GO TO 7.

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

  7. CHECK FUSE 
    1. Disconnect 20A fuse.
    2. Check 20A fuse for blown.

    OK or NG

    OK: GO TO 8.

    NG: Replace 20A fuse.

  8. CHECK INTERMITTENT INCIDENT 

    Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .

    OK or NG

    OK: Replace IPDM E/R. Refer to FUSES & CIRCUIT BREAKERS .

    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
      G02691570Courtesy of NISSAN MOTOR CO., U.S.A.
      Fig 5: Locating Throttle Position Sensor & Throttle Control Motor Harness Connector
      G02691571Courtesy of NISSAN MOTOR CO., U.S.A.
    5. Also check harness for short to ground and short to power. 

    OK or NG

    OK: GO TO 10.

    NG: Repair or replace.

  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

    OK: GO TO 11.

    NG: Remove the foreign matter and clean the electric throttle control actuator inside.

    Fig 6: Locating Electric Throttle Control Actuator
    G02691572Courtesy of NISSAN MOTOR CO., U.S.A.
  11. CHECK THROTTLE CONTROL MOTOR 

    Refer to COMPONENT INSPECTION .

    OK or NG

    OK: GO TO 12.

    NG: GO TO  13.

  12. CHECK INTERMITTENT INCIDENT 

    Refer to TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT .

    OK or NG

    OK: GO TO 13.

    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 .

      : INSPECTION END