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Home >> Lexus >> 2023 >> ES 350 Base >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Airbag System (Except Hybrid) - Diagnostic Codes (2 Of 3) >> AIRBAG SYSTEM (for Gasoline Model) >> DTC B1653: Driver Side Seat Position Sensor [06/2018 - 08/2021] >> Procedure

DTC B1653: Driver Side Seat Position Sensor [06/2018 - 08/2021]: Procedure

  1. CHECK VEHICLE CONDITION 
    1. Choose the model to be inspected.

      Result

      Result Proceed to
      for TMC Made A
      for TMMK Made B

    Result: 

    B 

    See step  9

    Result: 

    A 

    See step  2

  2. CHECK CONNECTION OF CONNECTORS 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

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

    3. Check that the connectors are properly connected to the airbag ECU assembly, front seat inner belt assembly LH and seat position airbag sensor.

      OK

      The connectors are properly connected.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    CONNECT CONNECTORS PROPERLY 

    Result: 

    OK 

    See step  3

  3. CHECK CONNECTORS 
    1. Disconnect the connectors from the airbag ECU assembly, front seat inner belt assembly LH and seat position airbag sensor.
    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, FRONT SEAT NO. 3 WIRE LH OR FRONT SEAT INNER BELT ASSEMBLY LH 

    Result: 

    OK 

    See step  4

  4. CHECK WIRE HARNESS 
    1. Connect the floor wire and front seat No. 3 wire LH to the front seat inner belt assembly LH.
      GTY824202Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Seat Position Airbag Sensor *2 Front Seat Inner Belt Assembly LH
      *3 Airbag ECU Assembly *4 Front Seat No. 3 Wire LH
      *5 Floor Wire *6 Service Wire
      *a Front view of wire harness connector
      (to Airbag ECU Assembly)      		 *b Front view of wire harness connector
      (to Seat Position Airbag Sensor)
    2. Connect the cable to the negative (-) battery terminal.
    3. Turn the engine switch on (IG).
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      U61-2 (LSP+) - Body ground Engine switch on (IG) Below 1 V
      U61-1 (LSP-) - Body ground Engine switch on (IG) Below 1 V
    5. Turn the engine switch off.
    6. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

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

    7. Using a service wire, connect terminals 25 (LSP+) and 26 (LSP-) 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
      U61-2 (LSP+) - U61-1 (LSP-) 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
      U61-2 (LSP+) - U61-1 (LSP-) Always 1 MΩ or higher
      U61-2 (LSP+) - Body ground Always 1 MΩ or higher
      U61-1 (LSP-) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  7

    Result: 

    OK 

    See step  5

  5. CHECK DTC 
    1. Connect the connectors to the airbag ECU assembly and seat position airbag sensor.
      GTY749188Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Seat Position Airbag Sensor
      *2 Front Seat Inner Belt Assembly LH
      *3 Airbag ECU Assembly
    2. Connect the cable to the negative (-) battery terminal.
    3. Turn the engine 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 engine switch off.
    6. Turn the engine switch on (IG), and wait for at least 60 seconds.
    7. Check for DTCs.

      Body Electrical > SRS Airbag > Trouble Codes 

      OK

      DTC B1653 is not output.

      HINT: 

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

      Result

      Result
      OK
      NG

    Result: 

    OK 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [06/2018 - ] 

    Result: 

    NG 

    See step  6

  6. CHECK SEAT POSITION AIRBAG SENSOR 
    1. Turn the engine switch off.
      GTY753173Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Seat Position Airbag Sensor
      *2 Front Seat Inner Belt Assembly LH
      *3 Airbag ECU Assembly
    2. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

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

    3. Replace the seat position airbag sensor with a known good one.

      Refer to REMOVAL [06/2018 - 08/2021]

      HINT: 

      Perform the following inspection using known good parts from another vehicle if possible.

    4. Connect the cable to the negative (-) battery terminal.
    5. Turn the engine switch on (IG), and wait for at least 60 seconds.
    6. Clear the DTCs stored in memory.

      Body Electrical > SRS Airbag > Clear DTCs 

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

      Body Electrical > SRS Airbag > Trouble Codes 

      OK

      DTC B1653 is not output.

      HINT: 

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

    10. Turn the engine switch off.
    11. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

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

    12. Restore the seat position airbag sensor that was installed for testing to its original location.

      Refer to REMOVAL [06/2018 - 08/2021]

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SEAT POSITION AIRBAG SENSOR. Refer to  REMOVAL [06/2018 - 08/2021] 

    Result: 

    NG 

    REPLACE AIRBAG ECU ASSEMBLY. Refer to  REMOVAL [06/2018 - 08/2020]  , or refer to  REMOVAL [08/2020 - 08/2021] 

  7. CHECK WIRE HARNESS 
    1. Disconnect the front seat No. 3 wire LH connector from the front seat inner belt assembly LH.
      GTY805075Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Seat Position Airbag Sensor *2 Front Seat Inner Belt Assembly LH
      *3 Airbag ECU Assembly *4 Front Seat No. 3 Wire LH
      *5 Floor Wire *6 Service Wire
      *a Front view of wire harness connector
      (to Airbag ECU Assembly)      		 *b Front view of wire harness connector
      (to Front Seat No. 3 Wire LH)
    2. Connect the cable to the negative (-) battery terminal.
    3. Turn the engine switch on (IG).
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      U64-2 (LSP+) - Body ground Engine switch on (IG) Below 1 V
      U64-1 (LSP-) - Body ground Engine switch on (IG) Below 1 V
    5. Turn the engine switch off.
    6. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

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

    7. Using a service wire, connect terminals 25 (LSP+) and 26 (LSP-) 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
      U64-2 (LSP+) - U64-1 (LSP-) 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
      U64-2 (LSP+) - U64-1 (LSP-) Always 1 MΩ or higher
      U64-2 (LSP+) - Body ground Always 1 MΩ or higher
      U64-1 (LSP-) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE FRONT SEAT NO. 3 WIRE LH 

    Result: 

    NG 

    See step  8

  8. CHECK FLOOR WIRE 
    1. Disconnect the floor wire connector from the front seat inner belt assembly LH.
      GTY836644Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Seat Position Airbag Sensor *2 Front Seat Inner Belt Assembly LH
      *3 Airbag ECU Assembly *4 Front Seat No. 3 Wire LH
      *5 Floor Wire *6 Service Wire
      *a Front view of wire harness connector
      (to Airbag ECU Assembly)      		 *b Front view of wire harness connector
      (to Front Seat Inner Belt Assembly LH)
    2. Connect the cable to the negative (-) battery terminal.
    3. Turn the engine switch on (IG).
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      N67-4 (LSP+) - Body ground Engine switch on (IG) Below 1 V
      N67-3 (LSP-) - Body ground Engine switch on (IG) Below 1 V
    5. Turn the engine switch off.
    6. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

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

    7. Using a service wire, connect terminals 25 (LSP+) and 26 (LSP-) 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
      N67-4 (LSP+) - N67-3 (LSP-) 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
      N67-4 (LSP+) - N67-3 (LSP-) Always 1 MΩ or higher
      N67-4 (LSP+) - Body ground Always 1 MΩ or higher
      N67-3 (LSP-) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE FRONT SEAT INNER BELT ASSEMBLY LH. Refer to  REMOVAL [06/2018 - 08/2021] 

    Result: 

    NG 

    REPLACE FLOOR WIRE 

  9. CHECK CONNECTION OF CONNECTORS 
    1. Turn the engine switch off.
    2. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

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

    3. Check that the connectors are properly connected to the airbag ECU assembly, front seat inner belt assembly LH and seat position airbag sensor.

      OK

      The connectors are properly connected.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    CONNECT CONNECTORS PROPERLY 

    Result: 

    OK 

    See step  10

  10. CHECK CONNECTORS 
    1. Disconnect the connectors from the airbag ECU assembly, front seat inner belt assembly LH and seat position airbag sensor.
    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 SEAT INNER BELT ASSEMBLY LH 

    Result: 

    OK 

    See step  11

  11. CHECK WIRE HARNESS 
    1. Connect the connectors to the front seat inner belt assembly LH and floor wire.
      GTY829780Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Seat Position Airbag Sensor
      *2 Front Seat Inner Belt Assembly LH
      *3 Airbag ECU Assembly
      *4 Floor Wire
      *5 Service Wire
      *a Front view of wire harness connector
      (to Airbag ECU Assembly)
      *b Front view of wire harness connector
      (to Seat Position Airbag Sensor)
    2. Connect the cable to the negative (-) battery terminal.
    3. Turn the engine switch on (IG).
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      z14-2 (LSP+) - Body ground Engine switch on (IG) Below 1 V
      z14-1 (LSP-) - Body ground Engine switch on (IG) Below 1 V
    5. Turn the engine switch off.
    6. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

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

    7. Using a service wire, connect terminals 25 (LSP+) and 26 (LSP-) 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
      z14-2 (LSP+) - z14-1 (LSP-) 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
      z14-2 (LSP+) - z14-1 (LSP-) Always 1 MΩ or higher
      z14-2 (LSP+) - Body ground Always 1 MΩ or higher
      z14-1 (LSP-) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  14

    Result: 

    OK 

    See step  12

  12. CHECK DTC 
    1. Connect the connectors to the airbag ECU assembly and seat position airbag sensor.
      GTY753173Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Seat Position Airbag Sensor
      *2 Front Seat Inner Belt Assembly LH
      *3 Airbag ECU Assembly
    2. Connect the cable to the negative (-) battery terminal.
    3. Turn the engine 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 engine switch off.
    6. Turn the engine switch on (IG), and wait for at least 60 seconds.
    7. Check for DTCs.

      Body Electrical > SRS Airbag > Trouble Codes 

      OK

      DTC B1653 is not output.

      HINT: 

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

      Result

      Result
      OK
      NG

    Result: 

    OK 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [06/2018 - ] 

    Result: 

    NG 

    See step  13

  13. CHECK SEAT POSITION AIRBAG SENSOR 
    1. Turn the engine switch off.
      GTY753173Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Seat Position Airbag Sensor
      *2 Front Seat Inner Belt Assembly LH
      *3 Airbag ECU Assembly
    2. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

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

    3. Replace the seat position airbag sensor with a known good one.

      Refer to REMOVAL [06/2018 - 08/2021]

      HINT: 

      Perform the following inspection using known good parts from another vehicle if possible.

    4. Connect the cable to the negative (-) battery terminal.
    5. Turn the engine switch on (IG), and wait for at least 60 seconds.
    6. Clear the DTCs stored in memory.

      Body Electrical > SRS Airbag > Clear DTCs 

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

      Body Electrical > SRS Airbag > Trouble Codes 

      OK

      DTC B1653 is not output.

      HINT: 

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

    10. Turn the engine switch off.
    11. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

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

    12. Restore the seat position airbag sensor that was installed for testing to its original location.

      Refer to REMOVAL [06/2018 - 08/2021]

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SEAT POSITION AIRBAG SENSOR. Refer to  REMOVAL [06/2018 - 08/2021] 

    Result: 

    NG 

    REPLACE AIRBAG ECU ASSEMBLY. Refer to  REMOVAL [06/2018 - 08/2020]  , or refer to  REMOVAL [08/2020 - 08/2021] 

  14. CHECK FLOOR WIRE 
    1. Disconnect the floor wire connector from the front seat inner belt assembly LH.
      GTY809475Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Seat Position Airbag Sensor
      *2 Front Seat Inner Belt Assembly LH
      *3 Airbag ECU Assembly
      *4 Floor Wire
      *5 Service Wire
      *a Front view of wire harness connector
      (to Airbag ECU Assembly)
      *b Front view of wire harness connector
      (to Front Seat Inner Belt Assembly LH)
    2. Connect the cable to the negative (-) battery terminal.
    3. Turn the engine switch on (IG).
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      N67-4 (LSP+) - Body ground Engine switch on (IG) Below 1 V
      N67-3 (LSP-) - Body ground Engine switch on (IG) Below 1 V
    5. Turn the engine switch off.
    6. Disconnect the cable from the negative (-) battery terminal.
      WARNING:

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

    7. Using a service wire, connect terminals 25 (LSP+) and 26 (LSP-) 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
      N67-4 (LSP+) - N67-3 (LSP-) 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
      N67-4 (LSP+) - N67-3 (LSP-) Always 1 MΩ or higher
      N67-4 (LSP+) - Body ground Always 1 MΩ or higher
      N67-3 (LSP-) - Body ground Always 1 MΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE FRONT SEAT INNER BELT ASSEMBLY LH. Refer to  REMOVAL [06/2018 - 08/2021] 

    Result: 

    NG 

    REPLACE FLOOR WIRE 

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