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Home >> Infiniti >> 2006 >> QX56 RWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Introduction >> Power Supply And Ground Circuit >> Diagnostic Procedure
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Diagnostic Procedure

  1. INSPECTION START 

    Start engine.

    Is engine running? 

    Yes or No 

    1. Yes : GO TO  8.
    2. No : GO TO 2.
  2. CHECK ECM POWER SUPPLY CIRCUIT-I 
    1. Turn ignition switch OFF and then ON.
    2. Check voltage between ECM terminal 109 and ground with CONSULT-II or tester.

      Voltage: Battery voltage 

    OK or NG 

    1. OK : GO TO  4.
    2. NG : GO TO 3.
      Fig 1: Identifying Voltage Between ECM Terminal 109 & Ground
      G04132646Courtesy of NISSAN MOTOR CO., U.S.A.
  3. DETECT MALFUNCTIONING PART 

    Check the following.

    • 10A fuse
    • Harness for open or short between ECM and fuse
    1. : Repair harness or connectors.
  4. CHECK GROUND CONNECTIONS 
    1. Turn ignition switch OFF.
    2. Loosen and retighten three ground screws on the body.

      Refer to "GROUND INSPECTION ".

      Fig 2: Identifying Ground Connections
      G04132647Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK : GO TO 5.
    2. NG : Repair or replace ground connections.
  5. CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT-I 
    1. Disconnect ECM harness connector.
    2. Check harness continuity between ECM terminals 1, 115, 116 and ground.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

    3. Also check harness for short to power.

    OK or NG 

    1. OK : GO TO  7.
    2. NG : GO TO 6.
  6. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors F32, E2
    • Harness for open or short between ECM and ground
    1. : Repair open circuit or short to power in harness or connectors.
  7. CHECK ECM POWER SUPPLY CIRCUIT-II 
    1. Reconnect ECM harness connector.
    2. Turn ignition switch ON.
    3. Check voltage between IPDM E/R terminal 4 and ground with CONSULT-II or tester.

      Voltage: Battery voltage 

    OK or NG 

    1. OK : Go to "IGNITION SIGNAL ".
    2. NG : GO TO 8.
      Fig 3: Identifying Voltage Between IPDM E/R Terminal 4 & Ground
      G04132648Courtesy of NISSAN MOTOR CO., U.S.A.
  8. CHECK ECM POWER SUPPLY CIRCUIT-III 
    1. Turn ignition switch OFF and wait at least 10 seconds.
    2. Turn ignition switch ON and then OFF.
    3. Check voltage between ECM terminals 119, 120 and ground with CONSULT-II or tester.

      Voltage: After turning ignition switch OFF, battery voltage will exist for a few seconds, then drop approximately 0V. 

    OK or NG 

    1. OK : GO TO  13.
    2. NG (Battery voltage does not exist.) : GO TO 9.
    3. NG (Battery voltage exists for more than a few seconds.) : GO TO  11.
      Fig 4: Identifying Voltage Between ECM Terminals 119, 120 & Ground
      G04132649Courtesy of NISSAN MOTOR CO., U.S.A.
  9. CHECK ECM POWER SUPPLY CIRCUIT-IV 
    1. Turn ignition switch OFF and wait at least 10 seconds.
    2. Check voltage between ECM terminal 111 and ground with CONSULT-II or tester.

      Voltage: Battery voltage 

    OK or NG 

    1. OK : GO TO 10.
    2. NG : GO TO  11.
      Fig 5: Identifying Voltage Between ECM Terminal 111 & Ground
      G04132650Courtesy of NISSAN MOTOR CO., U.S.A.
  10. CHECK ECM POWER SUPPLY CIRCUIT-V 
    1. Disconnect ECM harness connector.
    2. Disconnect IPDM E/R harness connector E119.
    3. Check harness continuity between ECM terminals 119, 120 and IPDM E/R terminal 3.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

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

    OK or NG 

    1. OK : GO TO  13.
    2. NG : Repair open circuit or short to ground or short to power in harness or connectors.
  11. CHECK ECM POWER SUPPLY CIRCUIT-VI 
    1. Disconnect ECM harness connector.
    2. Disconnect IPDM E/R harness connector E119.
    3. Check harness continuity between ECM terminal 111 and IPDM E/R terminal 7.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

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

    OK or NG 

    1. OK : GO TO 12.
    2. NG : Repair open circuit or short to ground or short to power in harness or connectors.
  12. CHECK 20A FUSE 
    1. Disconnect 20A fuse from IPDM E/R.
    2. Check 20A fuse.

    OK or NG 

    1. OK : GO TO  16.
    2. NG : Replace 20A fuse.
  13. CHECK GROUND CONNECTIONS 
    1. Turn ignition switch OFF.
    2. Loosen and retighten ground three screws on the body.

      Refer to "GROUND INSPECTION ".

      Fig 6: Locating Body Ground Screws
      G04185036Courtesy of NISSAN MOTOR CO., U.S.A.

    OK or NG 

    1. OK : GO TO 14.
    2. NG : Repair or replace ground connections.
  14. CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT-II 
    1. Disconnect ECM harness connector.
    2. Check harness continuity between ECM terminals 1, 115, 116 and ground.

      Refer to WIRING DIAGRAM .

      Continuity should exist. 

    3. Also check harness for short to power.

    OK or NG 

    1. OK : GO TO  16.
    2. NG : GO TO 15.
  15. DETECT MALFUNCTIONING PART 

    Check the following.

    • Harness connectors F32, E2
    • Harness for open or short between ECM and ground
    1. : Repair open circuit or short to power in harness or connectors.
  16. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT ".

    OK or NG 

    1. OK : Replace IPDM E/R.
    2. NG : Repair open circuit or short to power in harness or connectors.
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