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Home >> Infiniti >> 2018 >> QX30 Essential, FWD >> Repair and Diagnosis >> Accessories & Equipment >> Communication Devices >> Can System (Circuit Diagnosis) >> Circuit Diagnosis >> BCM - Left Front Door Control Unit Circuit >> Diagnosis Procedure

Diagnosis Procedure

  1. CHECK HARNESS CONNECTOR CONNECTION 

    Check the following harness connector for disconnection or looseness.

    • BCM
    • Harness connector M59
    • Harness connector D32
    • Left front door control unit

    Is the inspection result normal?

    YES

    GO TO 2.

    NO

    Securely connect the harness connectors.

  2. CHECK POWER SUPPLY AND GROUND CIRCUIT 

    Check power supply and ground circuit for the following unit.

    Is the inspection result normal?

    YES

    GO TO 3.

    NO

    Repair or replace the malfunctioning part.

  3. CHECK CIRCUIT (SHORT TO BATTERY) 
    1. Turn ignition switch OFF.
    2. Disconnect the following unit connectors.
      • BCM
      • Left front door control unit
    3. Check voltage between BCM harness connector and ground.

      Terminals

      Voltage

      (Approx.)

      +

      -

      BCM

      Ground

      Connector

      Terminal

      M25

      8

      --

      0 V

      9

    Is the inspection result normal?

    YES

    GO TO 4.

    NO

    Repair or replace harness.

  4. CHECK CIRCUIT (SHORT TO GROUND) 

    Check continuity between BCM harness connector and ground.

    BCM

    Ground

    Continuity

    Connector

    Terminal

    M25

    8

    --

    Not existed

    9

    Is the inspection result normal?

    YES

    GO TO 5.

    NO

    Repair or replace harness.

  5. CHECK CIRCUIT (SHORT WITH CAN-H AND CAN-L) 

    Check continuity between BCM harness connector terminals.

    BCM

    Continuity

    Connector

    Terminal

    Connector

    Terminal

    M25

    8

    M25

    9

    Not existed

    Is the inspection result normal?

    YES

    GO TO 6.

    NO

    Repair or replace harness.

  6. CHECK CIRCUIT (OPEN) 

    Check continuity between the following unit harness connectors.

    • BCM
    • Left front door control unit
      BCM - Left front door control unit

      BCM

      Left front door control unit

      Continuity

      Connector

      Terminal

      Connector

      Terminal

      M25

      8

      D12

      22

      Existed

      9

      21

    Is the inspection result normal?

    YES

    INSPECTION END

    NO

    Repair or replace harness.