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Home >> Subaru >> 2019 >> BRZ Limited, Automatic Trans >> Repair and Diagnosis (Single Page) >> Restraints >> Air Bag, SRS >> Air Bag System (Diagnostics) >> SRS Airbag System >> DTC B1637: Curtain Airbag Sensor LH Lost Communication; DTC B1638: Curtain Airbag Sensor LH Initialization Error >> Inspection steps

Inspection steps

CAUTION: Before performing the diagnosis, refer to the PRECAUTIONS .
  1. Check DTC
    1. Check for DTC.

      Criteria: DTC B1627 and B1628 are not displayed.

    NG: Perform diagnosis for the displayed DTC B1627 and B1628.

    OK: Go to next step

  2. Check poor contact of connectors.
    1. Check for poor contact of the connectors between the airbag control module and the curtain airbag sensor LH.

      Criteria: No fault is found.

    NG: Replace the airbag rear harness along with the body harness.

    OK: Go to next step

  3. Check airbag rear harness (between side airbag sensor and curtain airbag sensor LH).
    1. Turn the ignition switch to OFF, disconnect the battery ground terminal, and wait for 60 seconds or more.
    2. Disconnect the connector (H22) from the seat belt pretensioner LH.
    3. Disconnect the connector (H30) from the curtain airbag module LH.
    4. Disconnect the connector (Hb1) of the side airbag module LH.
    5. Disconnect the connector (H23) of the side airbag sensor LH.
    6. Connect the connector B of the side airbag sensor LH and the connector (1AI) in the test harness AI.
    7. Connect the connector (2AI) in the test harness AI and the connector (1V) in the test harness V.
    8. Disconnect the connector C from the curtain airbag sensor LH, and connect to the connector (2V) in the test harness V.
    9. Measure the resistance between the terminals.
    STANDARD VALUE RESISTANCE SPECIFICATION

    Inspection terminals Inspection conditions Standard value
    (3V) No. 2 - (3V) No. 6 Always Less than 10 Ω
    (3V) No. 1 - (3V) No. 7 Always Less than 10 Ω
    G12589678Courtesy of SUBARU OF AMERICA, INC.

    NG: Replace the airbag rear harness along with the body harness.

    OK: Go to next step

  4. Check airbag rear harness (between side airbag sensor and curtain airbag sensor LH).
    1. Measure the resistance between the terminals.
    STANDARD VALUE RESISTANCE SPECIFICATION

    Inspection terminals Inspection conditions Standard value
    (3V) No. 1 - chassis ground Always 1 MΩ or more
    (3V) No. 2 - chassis ground Always 1 MΩ or more
    (3V) No. 1 - (3V) No. 2 Always 1 MΩ or more
    G12589679Courtesy of SUBARU OF AMERICA, INC.

    NG: Replace the airbag rear harness along with the body harness.

    OK: Go to next step

  5. Check DTC
    1. Connect all connectors.
    2. Clear the memory.
    3. Perform the reproduction procedure.
    4. Read the DTC. (Current malfunction)

      Criteria: DTC B1638 is displayed.

    G12589680Courtesy of SUBARU OF AMERICA, INC.

    NG: Go to step  7.

    OK: Go to next step

  6. Check DTC
    1. Turn the ignition switch to OFF, disconnect the battery ground terminal, and wait for 60 seconds or more.
    2. Replace the curtain airbag sensor LH.
    3. Connect all connectors.
    4. Clear the memory.
    5. Perform the reproduction procedure.
    6. Read the DTC. (Current malfunction)

      Criteria: DTC B1638 is displayed.

    G12589681Courtesy of SUBARU OF AMERICA, INC.

    NG: Go to step  8.

    OK: Go to next step

  7. Check DTC
    1. Turn the ignition switch to OFF, disconnect the battery ground terminal, and wait for 60 seconds or more.
    2. Replace the side airbag sensor LH.
    3. Connect all connectors.
    4. Clear the memory.
    5. Perform the reproduction procedure.
    6. Read the DTC. (Current malfunction)

      Criteria: DTC B1638 is displayed.

    G12589682Courtesy of SUBARU OF AMERICA, INC.

    NG: Go to step  8.

    OK: Go to next step

    Replace the airbag control module.

  8. Check DTC

    Criteria: No other DTC is displayed.

    NG: Perform diagnosis for the displayed DTC.

    OK: Go to next step

    Complete

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