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Home >> Toyota >> 2020 >> Avalon Limited >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 53 (Supplemental Restraint System - Diagnostic Codes (B1160-B1653) (Hybrid)) >> AIRBAG SYSTEM (for HV Model) >> DTC B1637: Curtain Shield Airbag Sensor Lost Communication (LH); DTC B1638: Curtain Shield Airbag Sensor Initialization Error (LH) [04/2018 -] >> Procedure

DTC B1637: Curtain Shield Airbag Sensor Lost Communication (LH); DTC B1638: Curtain Shield Airbag Sensor Initialization Error (LH) [04/2018 -]: Procedure

WARNING: This page is about a different variant/trim than selected.
  1. CHECK CONNECTION OF CONNECTORS 
    1. Turn the power switch off.
    2. Disconnect the cable from the negative (-) auxiliary battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.

    3. Check that the connectors are properly connected to the airbag ECU assembly, side airbag pressure sensor LH and side No. 2 airbag sensor LH. Also check that the connectors that link the floor wire and front door wire LH are properly connected.

      OK

      The connectors are properly connected.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    CONNECT CONNECTORS PROPERLY 

    Result: 

    OK 

    See step  2

  2. CHECK CONNECTORS 
    1. Disconnect the connectors from the airbag ECU assembly, side airbag pressure sensor LH and side No. 2 airbag sensor LH. Also disconnect the connectors that link the floor wire and front door wire LH.
    2. Check that the terminals of the connectors are not deformed or damaged.

      OK

      The terminals are not deformed or damaged.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FLOOR WIRE OR FRONT DOOR WIRE LH 

    Result: 

    OK 

    See step  3

  3. CHECK FLOOR WIRE 
    1. Connect the cable to the negative (-) auxiliary battery terminal.
      GTY850547Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Side No. 2 Airbag Sensor LH
      *2 Airbag ECU Assembly
      *3 Floor Wire
      *4 Service Wire
      *a Front view of wire harness connector
      (to Airbag ECU Assembly)
      *b Front view of wire harness connector
      (to Side No. 2 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 Condition Specified Condition
      K31-4 (BCL+) - Body ground Power switch on (IG) Below 1 V
      K31-3 (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.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.

    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 the wire.

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      K31-4 (BCL+) - K31-3 (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
      K31-4 (BCL+) - K31-3 (BCL-) Always 1 MΩ or higher
      K31-4 (BCL+) - Body ground Always 1 MΩ or higher
      K31-3 (BCL-) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FLOOR WIRE 

    Result: 

    OK 

    See step  4

  4. CHECK WIRE HARNESS 
    1. Connect the connectors that link the floor wire and front door wire LH.
      GTY939066Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Side Airbag Pressure Sensor LH
      *2 Side No. 2 Airbag Sensor LH
      *3 Front Door Wire LH
      *4 Floor Wire
      *5 Service Wire
      *a Front view of wire harness connector
      (to Side No. 2 Airbag Sensor LH)
      *b Front view of wire harness connector
      (to Side Airbag Pressure Sensor LH)
    2. Connect the cable to the negative (-) auxiliary battery terminal.
    3. Turn the power switch on (IG).
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      K31-1 (BDL+) - Body ground Power switch on (IG) Below 1 V
      K31-2 (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.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.

    7. Using a service wire, connect terminals 2 (BDL+) and 1 (BDL-) of connector E.
      NOTE:

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

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      K31-1 (BDL+) - K31-2 (BDL-) Always Below 1 Ω
    9. Disconnect the service wire from connector E.
    10. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      K31-1 (BDL+) - K31-2 (BDL-) Always 1 MΩ or higher
      K31-1 (BDL+) - Body ground Always 1 MΩ or higher
      K31-2 (BDL-) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  7

    Result: 

    OK 

    See step  5

  5. CHECK SIDE NO. 2 AIRBAG SENSOR LH 
    1. Connect the connectors to the side airbag pressure sensor LH and airbag ECU assembly.
      GTY447346Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Side No. 2 Airbag Sensor RH
      *2 Airbag ECU Assembly
    2. Interchange the side No. 2 airbag sensor LH with RH and connect the connectors.
    3. Connect the cable to the negative (-) auxiliary battery terminal.
    4. Turn the power switch on (IG), and wait for at least 60 seconds.
    5. Clear the DTCs stored in memory.

      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.

      Body Electrical > SRS Airbag > Trouble Codes 

      HINT: 

      Codes other than DTCs B1632, B1633, B1637 and B1638 may be output at this time, but they are not related to this check.

      Result

      Result Proceed to
      DTC B1637 or B1638 is output. A
      DTC B1632 or B1633 is output. B
      DTCs B1632, B1633, B1637 and B1638 are not output. C
    9. Turn the power switch off.
    10. Disconnect the cable from the negative (-) auxiliary battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.

    11. Return the side No. 2 airbag sensor LH and RH to their original positions and connect the connectors.

    Result: 

    B 

    REPLACE SIDE NO. 2 AIRBAG SENSOR LH. Refer to  REMOVAL [04/2018 - 08/2020]  , or refer to  REMOVAL [08/2020 - 08/2021]  , or refer to  REMOVAL [08/2021 -] 

    Result: 

    C 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [04/2018 -] 

    Result: 

    A 

    See step  6

  6. CHECK SIDE AIRBAG PRESSURE SENSOR LH 
    1. Interchange the side airbag pressure sensor LH with RH and connect the connectors.
      GTY430525Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Side Airbag Pressure Sensor RH
      *2 Side No. 2 Airbag Sensor LH
    2. Connect the cable to the negative (-) auxiliary battery terminal.
    3. Turn the power switch on (IG), and wait for at least 60 seconds.
    4. Clear the DTCs stored in memory.

      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.

      Body Electrical > SRS Airbag > Trouble Codes 

      HINT: 

      Codes other than DTCs B1632, B1633, B1637 and B1638 may be output at this time, but they are not related to this check.

      Result

      Result Proceed to
      DTC B1637 or B1638 is output. A
      DTC B1632 or B1633 is output. B
      DTCs B1632, B1633, B1637 and B1638 are not output. C
    8. Turn the power switch off.
    9. Disconnect the cable from the negative (-) auxiliary battery terminal.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.

    10. Return the side airbag pressure sensor LH and RH to their original positions and connect the connectors.

    Result: 

    A 

    REPLACE AIRBAG ECU ASSEMBLY. Refer to  REMOVAL [04/2018 - 08/2020]  , or refer to  REMOVAL [08/2020 - 08/2021]  , or refer to  REMOVAL [08/2021 -] 

    Result: 

    B 

    REPLACE SIDE AIRBAG PRESSURE SENSOR LH. Refer to  REMOVAL [04/2018 - 08/2020]  , or refer to  REMOVAL [08/2020 - 08/2021]  , or refer to  REMOVAL [08/2021 -] 

    Result: 

    C 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [04/2018 -] 

  7. CHECK FLOOR WIRE 
    1. Disconnect the floor wire connector from the front door wire LH.
      GTY914214Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Side Airbag Pressure Sensor LH
      *2 Side No. 2 Airbag Sensor LH
      *3 Front Door Wire LH
      *4 Floor Wire
      *5 Service Wire
      *a Front view of wire harness connector
      (to Side No. 2 Airbag Sensor LH)
      *b Front view of wire harness connector
      (to Front Door Wire LH)
    2. Connect the cable to the negative (-) auxiliary battery terminal.
    3. Turn the power switch on (IG).
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      IK2-23 (BDL+) - Body ground Power switch on (IG) Below 1 V
      IK2-41 (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.
      WARNING:

      Wait at least 90 seconds after disconnecting the cable from the negative (-) auxiliary battery terminal to disable the SRS system.

    7. Using a service wire, connect terminals 1 (BDL+) and 2 (BDL-) of connector B.
      NOTE:

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

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      IK2-23 (BDL+) - IK2-41 (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
      IK2-23 (BDL+) - IK2-41 (BDL-) Always 1 MΩ or higher
      IK2-23 (BDL+) - Body ground Always 1 MΩ or higher
      IK2-41 (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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