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Home >> Lexus >> 2021 >> LS 500h RWD >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Airbag System (W/O Advanced Park) - Diagnostic Codes (1 Of 3) >> AIRBAG SYSTEM (w/o Advanced Park) >> DTC B1638: Curtain Shield Airbag Sensor Initialization Error (LH) [11/2021 - 10/2023] >> Procedure

DTC B1638: Curtain Shield Airbag Sensor Initialization Error (LH) [11/2021 - 10/2023]: Procedure

  1. CHECK PAST DTC 
    1. Turn the power switch on (IG), and wait for at least 60 seconds.
    2. Check for DTCs.

      Refer to DTC CHECK / CLEAR [10/2020 - 10/2023]

      Body Electrical > SRS Airbag > Trouble Codes 

      Result

      Proceed to
      DTC B1637 is not output
      DTC B1637 is output

    Result: 

    DTC B1637 is output 

    GO TO DTC B1637. Refer to  DTC B1635: Curtain Shield Airbag Sensor (LH); DTC B1637: Curtain Shield Airbag Sensor Lost Communication (LH) [11/2021 - 10/2023]  

    Result: 

    DTC B1637 is not output 

    See step  2

  2. CHECK DTC 
    1. Turn the power switch off.
    2. Turn the power switch on (IG), and wait for at least 60 seconds.
    3. Check for DTCs.

      Refer to DTC CHECK / CLEAR [10/2020 - 10/2023]

      Body Electrical > SRS Airbag > Trouble Codes 

      Result

      Proceed to
      DTC B1638 is output
      DTC B1638 is not output

      HINT: 

      Codes other than DTC B1638 may be output at this time, but they are not related to this check.

    Result: 

    DTC B1638 is not output 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2021 - 10/2022]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2022 - 10/2023] 

    Result: 

    DTC B1638 is output 

    See step  3

  3. CHECK CONNECTION OF CONNECTORS 
    1. Turn the power switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 60 seconds.
    3. Check that the connectors are properly connected to the airbag ECU assembly and rear airbag sensor LH.

      Result

      Proceed to
      The connectors are properly connected
      The connectors are not properly connected

    Result: 

    The connectors are not properly connected 

    CONNECT CONNECTORS PROPERLY 

    Result: 

    The connectors are properly connected 

    See step  4

  4. CHECK CONNECTORS 
    1. Disconnect the connectors from the airbag ECU assembly and rear airbag sensor LH.
    2. Check that the connectors (on the airbag ECU assembly side and rear airbag sensor LH side) are not damaged.
      GTY750510Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Airbag Sensor LH
      *2 Airbag ECU Assembly
      *3 Floor Wire

      Result

      Proceed to
      The connectors are not deformed or damaged
      The connectors are deformed or damaged

    Result: 

    The connectors are deformed or damaged 

    REPLACE FLOOR WIRE 

    Result: 

    The connectors are not deformed or damaged 

    See step  5

  5. CHECK FLOOR WIRE 
    1. Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.
      GTY835424Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Airbag Sensor LH
      *2 Airbag ECU Assembly
      *3 Floor Wire
      *4 Service Wire
      *a Front view of wire harness connector
      (to Rear Airbag Sensor LH)
      *b Front view of wire harness connector
      (to Airbag ECU Assembly)
    2. Turn the power switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      L63-4 (BCL+) - Body ground Power switch on (IG) Below 1 V
      L63-3 (BCL-) - Body ground Power switch on (IG) Below 1 V
    4. Turn the power switch off.
    5. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 60 seconds.
    6. Using a service wire, connect terminals 32 (BBL+) and 31 (BBL-) of connector B.
      NOTE:

      Do not forcibly insert the service wire into the terminals of the connector when connecting a service wire.

    7. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      L63-4 (BCL+) - L63-3 (BCL-) Always Below 1 Ω
    8. Disconnect the service wire from connector B.
    9. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      L63-4 (BCL+) - L63-3 (BCL-) Always 1 MΩ or higher
      L63-4 (BCL+) - Body ground Always 1 MΩ or higher
      L63-3 (BCL-) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FLOOR WIRE 

    Result: 

    OK 

    See step  6

  6. CHECK REAR AIRBAG SENSOR LH 
    1. Connect the connectors to the airbag ECU assembly.
      GTY783623Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Airbag Sensor RH
      *2 Airbag ECU Assembly
    2. Interchange the rear airbag sensor LH with RH and connect the connectors to them.
    3. Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.
    4. Turn the power switch on (IG), and wait for at least 60 seconds.
    5. Clear the DTCs stored in memory.

      Refer to DTC CHECK / CLEAR [10/2020 - 10/2023]

      Body Electrical > SRS Airbag > Clear DTCs 

    6. Turn the power switch off.
    7. Turn the power switch on (IG), and wait for at least 60 seconds.
    8. Check for DTCs.

      Refer to DTC CHECK / CLEAR [10/2020 - 10/2023]

      Body Electrical > SRS Airbag > Trouble Codes 

      Result

      Proceed to
      DTC B1633 is output
      DTC B1638 is output
      DTC B1633 and B1638 are not output

      HINT: 

      Codes other than DTC B1633 and B1638 may be output at this time, but they are not related to this check.

    9. Turn the power switch off.
    10. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 60 seconds.
    11. Return the rear airbag sensor RH and LH to their original positions and connect the connectors to them.

    Result: 

    DTC B1633 is output 

    REPLACE REAR AIRBAG SENSOR LH. Refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

    Result: 

    DTC B1633 and B1638 are not output 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2021 - 10/2022]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2022 - 10/2023] 

    Result: 

    DTC B1638 is output 

    See step  7

  7. CHECK CONNECTION OF CONNECTOR 
    1. Check that the connector is properly connected to the door side airbag sensor LH.

      Result

      Proceed to
      The connector is properly connected
      The connector is not properly connected

    Result: 

    The connector is not properly connected 

    CONNECT CONNECTOR PROPERLY 

    Result: 

    The connector is properly connected 

    See step  8

  8. CHECK CONNECTOR 
    1. Disconnect the connectors from the door side airbag sensor LH and rear airbag sensor LH.
    2. Check that the connector (on the door side airbag sensor LH side) is not damaged.
      GTY516347Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Door Side Airbag Sensor LH
      *2 Rear Airbag Assembly LH
      *3 Front Door Wire LH
      *4 Floor Wire

      Result

      Proceed to
      The connector is not deformed or damaged
      The connector is deformed or damaged

    Result: 

    The connector is deformed or damaged 

    REPLACE FRONT DOOR WIRE LH 

    Result: 

    The connector is not deformed or damaged 

    See step  9

  9. CHECK DOOR SIDE AIRBAG SENSOR LH CIRCUIT 
    1. Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.
      GTY1086431Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Door Side Airbag Sensor LH
      *2 Rear Airbag Sensor LH
      *3 Front Door Wire LH
      *4 Floor Wire
      *5 Service Wire
      *a Front view of wire harness connector
      (to Door Side Airbag Sensor LH)
      *b Front view of wire harness connector
      (to Rear Airbag Sensor LH)
    2. Turn the power switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      H27-2 (BDL+) - Body ground Power switch on (IG) Below 1 V
      H27-1 (BDL-) - Body ground Power switch on (IG) Below 1 V
    4. Turn the power switch off.
    5. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 60 seconds.
    6. Using a service wire, connect terminals 1 (BBL+) and 2 (BBL-) of connector B.
      NOTE:

      Do not forcibly insert the service wire into the terminals of the connector when connecting a service wire.

    7. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      H27-2 (BDL+) - H27-1 (BDL-) Always Below 1 Ω
    8. Disconnect the service wire from connector B.
    9. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      H27-2 (BDL+) - H27-1 (BDL-) Always 1 MΩ or higher
      H27-2 (BDL+) - Body ground Always 1 MΩ or higher
      H27-1 (BDL-) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  11

    Result: 

    OK 

    See step  10

  10. CHECK DTC 
    1. Connect the connectors to the door side airbag sensor LH and rear airbag sensor LH.
      GTY373590Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Door Side Airbag Sensor LH
      *2 Rear Airbag Sensor LH
    2. Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.
    3. Turn the power switch on (IG), and wait for at least 60 seconds.
    4. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [10/2020 - 10/2023]

      Body Electrical > SRS Airbag > Clear DTCs 

    5. Turn the power switch off.
    6. Turn the power switch on (IG), and wait for at least 60 seconds.
    7. Check for DTCs.

      Refer to DTC CHECK / CLEAR [10/2020 - 10/2023]

      Body Electrical > SRS Airbag > Trouble Codes 

      Result

      Proceed to
      DTC B1638 is output
      DTC B1638 is not output

      HINT: 

      Codes other than DTC B1638 may be output at this time, but they are not related to this check.

    Result: 

    DTC B1638 is output 

    REPLACE AIRBAG ECU ASSEMBLY. Refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

    Result: 

    DTC B1638 is not output 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2021 - 10/2022]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2022 - 10/2023] 

  11. CHECK FLOOR WIRE 
    1. Disconnect the floor wire connector from the front door wire LH.
      GTY1087357Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Door Side Airbag Sensor LH
      *2 Rear Airbag Sensor LH
      *3 Front Door Wire LH
      *4 Floor Wire
      *5 Service Wire
      *a Front view of wire harness connector
      (to Front Door Wire LH)
      *b Front view of wire harness connector
      (to Rear Airbag Sensor LH)
    2. Connect the cable to the negative (-) auxiliary battery terminal, and wait for at least 2 seconds.
    3. Turn the power switch on (IG).
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      L228-12 (BDL+) - Body ground Power switch on (IG) Below 1 V
      L228-22 (BDL-) - Body ground Power switch on (IG) Below 1 V
    5. Turn the power switch off.
    6. Disconnect the cable from the negative (-) auxiliary battery terminal, and wait for at least 60 seconds.
    7. Using a service wire, connect terminals 1 (BBL+) and 2 (BBL-) of connector B.
      NOTE:

      Do not forcibly insert the service wire into the terminals of the connector when connecting a service wire.

    8. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      L228-12 (BDL+) - L228-22 (BDL-) Always Below 1 Ω
    9. Disconnect the service wire from connector B.
    10. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      L228-12 (BDL+) - L228-22 (BDL-) Always 1 MΩ or higher
      L228-12 (BDL+) - Body ground Always 1 MΩ or higher
      L228-22 (BDL-) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE FRONT DOOR WIRE LH 

    Result: 

    NG 

    REPLACE FLOOR WIRE 

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