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Home >> Infiniti >> 2011 >> QX56 AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Introduction >> DTC/Circuit Diagnosis >> Power Supply And Ground Circuit >> Diagnosis Procedure
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Diagnosis Procedure

  1. CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT
    1. Disconnect ECM harness connector.
    2. Check the continuity between ECM harness connector and ground.
      CONTINUITY SPECIFICATION

      ECM Ground Continuity
      Connector Terminal
      F111 10 Ground Existed
      E80 174
      175
    3. Also check harness for short to power.

      Is the inspection result normal? 

      YES: GO TO  3.

      NO: GO TO 2.

  2. DETECT MALFUNCTIONING PART

    Check the following.

    • Loose or poor connection for each connector and harness
    • Harness for open or short between ECM and ground

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

  3. CHECK ECM POWER SUPPLY CIRCUIT-I
    1. Reconnect ECM harness connector.
    2. Turn ignition switch ON.
    3. Check the voltage between ECM harness connector terminals.
      VOLTAGE SPECIFICATION

      ECM Voltage
      Connector + -
      Terminal Terminal
      E80 141 175 Battery voltage

      Is the inspection result normal? 

      YES: GO TO  5.

      NO: GO TO 4.

  4. DETECT MALFUNCTIONING PART

    Check the following.

    • 10 A fuse (No. 62)
    • Loose or poor connection for each connector and harness
    • Harness for open or short between ECM and fuse

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

  5. CHECK ECM POWER SUPPLY CIRCUIT-II
    1. Turn ignition switch OFF and wait at least 10 seconds.
    2. Check the voltage between ECM harness connector terminals as per the following.
      VOLTAGE SPECIFICATION

      ECM Voltage
      Connector + -
      Terminal Terminal
      E80 171 175 After turning ignition switch OFF, battery voltage will exist for a few seconds, then drop to approximately 0 V.
      172

      Is the inspection result normal? 

      YES: GO TO 6.

      NO: GO TO  8.

  6. CHECK ECM POWER SUPPLY CIRCUIT-III
    1. Turn ignition switch ON.
    2. Check the voltage between IPDM E/R harness connector and ground.
      VOLTAGE SPECIFICATION

      IPDM E/R Ground Voltage
      Connector Terminal
      E15 61 Ground Battery voltage

      Is the inspection result normal? 

      YES: GO TO 7.

      NO: Replace IPDM E/R. Refer to "REMOVAL AND INSTALLATION ".

  7. CHECK INTERMITTENT INCIDENT

    Refer to "INTERMITTENT INCIDENT ".

    INSPECTION END

  8. CHECK ECM POWER SUPPLY CIRCUIT-IV
    1. Turn ignition switch OFF and wait at least 10 seconds.
    2. Check the voltage between ECM harness connector terminals as per the following.
      VOLTAGE SPECIFICATION

      ECM Voltage
      Connector + -
      Terminal Terminal
      E80 163 175 Battery voltage

      Is the inspection result normal? 

      YES: GO TO  12.

      NO: GO TO 9.

  9. CHECK ECM POWER SUPPLY CIRCUIT-V
    1. Disconnect ECM harness connector.
    2. Disconnect IPDM E/R harness connector.
    3. Check the continuity between ECM harness connector and IPDM E/R harness connector.
      CONTINUITY SPECIFICATION

      ECM IPDM E/R Continuity
      Connector Terminal Connector Terminal
      E80 163 E14 41 Existed
    4. Also check harness for short to ground and short to power.

      Is the inspection result normal? 

      YES: GO TO  11.

      NO: GO TO 10.

  10. DETECT MALFUNCTIONING PART

    Check the following.

    • Loose or poor connection for each connector and harness
    • Harness for open or short between ECM and IPDM E/R

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

  11. CHECK 20 A FUSE
    1. Disconnect 20 A fuse (No. 43) from IPDM E/R.
    2. Check 20 A fuse.

      Is the inspection result normal? 

      YES: GO TO  14.

      NO: Replace 15 A fuse.

  12. CHECK ECM POWER SUPPLY CIRCUIT-VI
    1. Disconnect ECM harness connector.
    2. Disconnect IPDM E/R harness connector.
    3. Check the continuity between ECM harness connector and IPDM E/R harness connector.
      CONTINUITY SPECIFICATION

      ECM IPDM E/R Continuity
      Connector Terminal Connector Terminal
      E80 171 E14 35 Existed
      172
    4. Also check harness for short to ground and short to power.

      Is the inspection result normal? 

      YES: GO TO  14.

      NO: GO TO 13.

  13. DETECT MALFUNCTIONING PART

    Check the following.

    • Loose or poor connection for each connector and harness
    • Harness for open or short between ECM and IPDM E/R

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

  14. CHECK INTERMITTENT INCIDENT

    Refer to "INTERMITTENT INCIDENT ".

    Is the inspection result normal? 

    YES: Replace IPDM E/R. Refer to "REMOVAL AND INSTALLATION ".

    NO: Repair open circuit, short to ground or short to power in harness or connectors.

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