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Home >> Infiniti >> 2012 >> M37 Base >> Repair and Diagnosis >> Steering >> Power Steering >> Steering Control System (With 4WAS) >> DTC/Circuit Diagnosis >> Power Supply And Ground Circuit >> Diagnosis Procedure (4WAS Front Control Unit)
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Diagnosis Procedure (4WAS Front Control Unit)

  1. CHECK 4WAS FRONT CONTROL UNIT POWER SUPPLY (1) 
    1. Turn the ignition switch OFF.
    2. Disconnect 4WAS front control unit harness connector.
    3. Check the voltage between 4WAS front control unit harness connector terminal and ground.
      4WAS front control unit - Voltage (Approx.)
      Connector Terminal
      M41 11 Ground Battery voltage
    4. Turn the ignition switch ON.
      CAUTION: Never start the engine.
    5. Check the voltage between 4WAS front control unit harness connector terminal and ground.
      4WAS front control unit - Voltage (Approx.)
      Connector Terminal
      M41 11 Ground Battery voltage

      Is the inspection result normal? 

      YES: GO TO  3.

      NO: GO TO 2.

  2. CHECK 4WAS FRONT CONTROL UNIT POWER SUPPLY (2) 
    1. Turn the ignition switch OFF.
    2. Check the 40A fusible link (Q).
    3. Check the harness for open or short between 4WAS front control unit harness connector No. 11 terminal and 40A fusible link (Q).

      Is the inspection result normal? 

      YES: Perform the trouble diagnosis for power supply circuit. Refer to "WIRING DIAGRAM - BATTERY POWER SUPPLY - ".

      NO: Repair or replace error-detected parts.

  3. CHECK 4WAS FRONT CONTROL UNIT POWER SUPPLY (3) 
    1. Turn the ignition switch OFF.
    2. Disconnect 4WAS front control unit harness connector.
    3. Check the voltage between 4WAS front control unit harness connector terminal and ground.
      4WAS front control unit - Voltage (Approx.)
      Connector Terminal
      M42 15 Ground 0 V
    4. Turn the ignition switch ON.
      CAUTION: Never start the engine.
    5. Check the voltage between 4WAS front control unit harness connector terminal and ground.
      4WAS front control unit - Voltage (Approx.)
      Connector Terminal
      M42 15 Ground Battery voltage

      Is the inspection result normal? 

      YES: GO TO  5.

      NO: GO TO 4.

  4. CHECK 4WAS FRONT CONTROL UNIT POWER SUPPLY (4) 
    1. Turn the ignition switch OFF.
    2. Check the 10A fuse (#3).
    3. Disconnect fuse block (J/B) harness connector.
    4. Check the continuity between 4WAS front control unit harness connector and fuse block (J/B).
      4WAS front control unit Fuse block (J/B) Continuity
      Connector Terminal Connector Terminal
      M42 15 M1 2A Existed
    5. Check the continuity between 4WAS front control unit harness connector and the ground.
      4WAS front control unit - Continuity
      Connector Terminal
      M42 15 Ground Not existed

      Is the inspection result normal? 

      YES: Perform the trouble diagnosis for ignition power supply circuit. Refer to "WIRING DIAGRAM - IGNITION POWER SUPPLY - ".

      NO: Repair or replace error-detected parts.

  5. CHECK 4WAS FRONT CONTROL UNIT GROUND 

    Check the continuity between 4WAS front control unit harness connector terminal and the ground.

    4WAS front control unit - Continuity
    Connector Terminal
    M41 12 Ground Existed
    M42 18
    34

    Is the inspection result normal? 

    YES: INSPECTION END

    NO: Repair or replace the harnesses and connectors.

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