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Home >> Lexus >> 2021 >> LC 500 2D Coupe >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Airbag System - Diagnostic Codes (Coupe) (2 Of 5) >> Airbag System >> DTC B1653/35: Seat Position Airbag Sensor Circuit Malfunction [03/2017 - 04/2020] >> Procedure

DTC B1653/35: Seat Position Airbag Sensor Circuit Malfunction [03/2017 - 04/2020]: Procedure

  1. CHECK CONNECTION OF CONNECTORS 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Check that the connectors are properly connected to the airbag ECU assembly and front seat adjuster assembly LH (seat position airbag sensor).

      Result

      Proceed to
      Connectors are properly connected
      Connectors are not properly connected

    Result: 

    Connectors are not properly connected 

    CONNECT CONNECTORS PROPERLY 

    Result: 

    Connectors are properly connected 

    See step  2

  2. CHECK CONNECTION OF CONNECTORS 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Check that the connectors are properly connected to the airbag ECU assembly and front seat adjuster assembly LH (seat position airbag sensor).

      Result

      Proceed to
      Connectors are properly connected
      Connectors are not properly connected

    Result: 

    Connectors are not properly connected 

    CONNECT CONNECTORS PROPERLY 

    Result: 

    Connectors are properly connected 

    See step  3

  3. CHECK CONNECTORS 
    1. Disconnect the connectors from the airbag ECU assembly and front seat adjuster assembly LH (seat position airbag sensor).
      GTY956917Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Adjuster Assembly LH (Seat Position Airbag Sensor)
      *2 Airbag ECU Assembly
      *3 Front Seat Wire LH
      *4 Front Seat Inner Belt Assembly LH
      *5 Floor Wire
    2. Check that the connectors (on the airbag ECU assembly side and front seat adjuster assembly LH (seat position airbag sensor) side) are not damaged.

      Result

      Proceed to
      Connectors are not deformed or damaged
      Connectors are deformed or damaged

    Result: 

    Connectors are deformed or damaged 

    REPLACE FLOOR WIRE OR FRONT SEAT WIRE LH 

    Result: 

    Connectors are not deformed or damaged 

    See step  4

  4. CHECK SEAT POSITION AIRBAG SENSOR CIRCUIT 
    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
      GTY957142Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Adjuster Assembly LH (Seat Position Airbag Sensor)
      *2 Airbag ECU Assembly
      *3 Front Seat Wire LH
      *4 Front Seat Inner Belt Assembly LH
      *5 Floor Wire
      *6 Service Wire
      *a Front view of wire harness connector
      (to Front Seat Adjuster Assembly LH (Seat Position Airbag Sensor))
      *b Front view of wire harness connector
      (to Airbag ECU Assembly)
    2. Turn the engine switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      w14-1 (GND) - Body ground Engine switch on (IG) Below 1 V
      w14-2 (VS) - Body ground Engine switch on (IG) Below 1 V
    4. Turn the engine switch off.
    5. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    6. Using a service wire, connect terminals 26 (LSP-) and 25 (LSP+) 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
      w14-1 (GND) - w14-2 (VS) 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
      w14-1 (GND) - w14-2 (VS) Always 1 MΩ or higher
      w14-1 (GND) - Body ground Always 1 MΩ or higher
      w14-2 (VS) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  8

    Result: 

    OK 

    See step  5

  5. CHECK DTC 
    1. Connect the connectors to the airbag ECU assembly and front seat adjuster assembly LH (seat position airbag sensor).
      GTY957185Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Adjuster Assembly LH (Seat Position Airbag Sensor)
      *2 Airbag ECU Assembly
    2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    3. Turn the engine switch on (IG), and wait for at least 60 seconds.
    4. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [03/2017 - 04/2020]

      Body Electrical > SRS Airbag > Clear DTCs 

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

      Refer to DTC CHECK / CLEAR [03/2017 - 04/2020]

      Body Electrical > SRS Airbag > Trouble Codes 

      Result

      Proceed to
      DTC B1653/35 is not output
      DTC B1653/35 is output

      HINT: 

      Codes other than DTC B1653/35 may be output at this time, but they are not related to this check.

    Result: 

    DTC B1653/35 is not output 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [03/2017 - 04/2020] 

    Result: 

    DTC B1653/35 is output 

    See step  6

  6. REPLACE FRONT SEAT ADJUSTER ASSEMBLY LH (SEAT POSITION AIRBAG SENSOR) 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Replace the front seat adjuster assembly LH (seat position airbag sensor).

      Refer to DISASSEMBLY [03/2017 - 04/2020]

      HINT: 

      Perform the inspection using parts from a normal vehicle if possible.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  7

  7. CHECK DTC 
    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
      GTY957185Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Adjuster Assembly LH (Seat Position Airbag Sensor)
      *2 Airbag ECU Assembly
    2. Turn the engine switch on (IG), and wait for at least 60 seconds.
    3. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [03/2017 - 04/2020]

      Body Electrical > SRS Airbag > Clear DTCs 

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

      Body Electrical > SRS Airbag > Trouble Codes 

      Result

      Proceed to
      DTC B1653/35 is not output
      DTC B1653/35 is output

      HINT: 

      Codes other than DTC B1653/35 may be output at this time, but they are not related to this check.

    Result: 

    DTC B1653/35 is not output 

    END (FRONT SEAT ADJUSTER ASSEMBLY LH (SEAT POSITION AIRBAG SENSOR) WAS DEFECTIVE) 

    Result: 

    DTC B1653/35 is output 

    REPLACE AIRBAG ECU ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

  8. CHECK CONNECTORS 
    1. Disconnect the connectors from the front seat wire LH and front seat inner belt assembly LH.
      GTY956208Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Adjuster Assembly LH (Seat Position Airbag Sensor)
      *2 Airbag ECU Assembly
      *3 Front Seat Wire LH
      *4 Front Seat Inner Belt Assembly LH
      *5 Floor Wire
    2. Check that the connectors (on the front seat wire LH side and front seat inner belt assembly LH side) are not damaged.

      Result

      Proceed to
      Connectors are not deformed or damaged
      Connectors are deformed or damaged

    Result: 

    Connectors are deformed or damaged 

    REPLACE FRONT SEAT WIRE LH OR FRONT SEAT INNER BELT ASSEMBLY LH 

    Result: 

    Connectors are not deformed or damaged 

    See step  9

  9. CHECK SEAT POSITION AIRBAG SENSOR CIRCUIT 
    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
      GTY957216Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Adjuster Assembly LH (Seat Position Airbag Sensor)
      *2 Airbag ECU Assembly
      *3 Front Seat Wire LH
      *4 Front Seat Inner Belt Assembly LH
      *5 Floor Wire
      *6 Service Wire
      *a Front view of wire harness connector
      (to Front Seat Adjuster Assembly LH (Seat Position Airbag Sensor))
      *b Front view of wire harness connector
      (to Airbag ECU Assembly)
    2. Turn the engine switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      w15-1 (LSP-) - Body ground Engine switch on (IG) Below 1 V
      w15-2 (LSP+) - Body ground Engine switch on (IG) Below 1 V
    4. Turn the engine switch off.
    5. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    6. Using a service wire, connect terminals 26 (LSP-) and 25 (LSP+) 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
      w15-1 (LSP-) - w15-2 (LSP+) 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
      w15-1 (LSP-) - w15-2 (LSP+) Always 1 MΩ or higher
      w15-1 (LSP-) - Body ground Always 1 MΩ or higher
      w15-2 (LSP+) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE FRONT SEAT WIRE LH 

    Result: 

    NG 

    See step  10

  10. CHECK CONNECTORS 
    1. Disconnect the connectors from the front seat inner belt assembly LH and floor wire.
      GTY957229Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Adjuster Assembly LH (Seat Position Airbag Sensor)
      *2 Airbag ECU Assembly
      *3 Front Seat Wire LH
      *4 Front Seat Inner Belt Assembly LH
      *5 Floor Wire
    2. Check that the connectors (on the front seat inner belt assembly LH side and floor wire side) are not damaged.

      Result

      Proceed to
      Connectors are not deformed or damaged
      Connectors are deformed or damaged

    Result: 

    Connectors are deformed or damaged 

    REPLACE FRONT SEAT INNER BELT ASSEMBLY LH OR FLOOR WIRE 

    Result: 

    Connectors are not deformed or damaged 

    See step  11

  11. CHECK FLOOR WIRE 
    1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
      GTY956404Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Front Seat Adjuster Assembly LH (Seat Position Airbag Sensor)
      *2 Airbag ECU Assembly
      *3 Front Seat Wire LH
      *4 Front Seat Inner Belt Assembly LH
      *5 Floor Wire
      *6 Service Wire
      *a Front view of wire harness connector
      (to Front Seat Adjuster Assembly LH (Seat Position Airbag Sensor))
      *b Front view of wire harness connector
      (to Airbag ECU Assembly)
    2. Turn the engine switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      X14-3 (LSP-) - Body ground Engine switch on (IG) Below 1 V
      X14-4 (LSP+) - Body ground Engine switch on (IG) Below 1 V
    4. Turn the engine switch off.
    5. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    6. Using a service wire, connect terminals 26 (LSP-) and 25 (LSP+) 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
      X14-3 (LSP-) - X14-4 (LSP+) 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
      X14-3 (LSP-) - X14-4 (LSP+) Always 1 MΩ or higher
      X14-3 (LSP-) - Body ground Always 1 MΩ or higher
      X14-4 (LSP+) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE FLOOR WIRE 

    Result: 

    NG 

    REPLACE FRONT SEAT INNER BELT ASSEMBLY LH. Refer to  REMOVAL [03/2017 - 05/2023] 

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