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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 (3 Of 3) >> AIRBAG SYSTEM (w/o Advanced Park) >> DTC B1925: Short in Rear P/T Squib LH Circuit; DTC B1926: Open in Rear P/T Squib LH Circuit; DTC B1927: Short in Rear P/T Squib LH Circuit (To Ground); DTC B1928: Short in Rear P/T Squib LH Circuit (To B+) [10/2020 - 10/2023] >> Procedure

DTC B1925: Short in Rear P/T Squib LH Circuit; DTC B1926: Open in Rear P/T Squib LH Circuit; DTC B1927: Short in Rear P/T Squib LH Circuit (To Ground); DTC B1928: Short in Rear P/T Squib LH Circuit (To B+) [10/2020 - 10/2023]: Procedure

  1. CHECK CONNECTORS 
    1. Turn the power switch off.
      GTY760542Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Outer Belt Assembly LH
      *2 Airbag ECU Assembly
      *3 Floor Wire
    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 rear seat outer belt assembly LH and airbag ECU assembly.

      OK

      The connectors are properly connected.

      HINT: 

      If the connectors are not properly connected, reconnect the connectors and proceed to the next inspection.

    4. Disconnect the connectors from the rear seat outer belt assembly LH and airbag ECU assembly.
    5. Check that the terminals of the connectors are not deformed or damaged.

      OK

      The terminals are not deformed or damaged.

    6. Check that the floor wire connector (on the rear seat outer belt assembly LH side) is not loose, deformed or damaged.

      OK

      The connector locking button is not disengaged, and the claw of the lock is not deformed or damaged.

    7. Check that the short springs of the activation prevention mechanism of the floor wire connector are not deformed or damaged.

      OK

      The short springs are not deformed or damaged.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FLOOR WIRE 

    Result: 

    OK 

    See step  2

  2. CHECK REAR SEAT OUTER BELT ASSEMBLY LH 
    1. Connect the connector to the airbag ECU assembly.
      GTY782617Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Outer Belt Assembly LH
      *2 Airbag ECU Assembly
      *3 SST
      *a Front view of wire harness connector
      (to Rear Seat Outer Belt Assembly LH)
    2. Connect the white wire side of SST (resistance: 2.1 Ω) to connector C.
      WARNING:

      Never connect the tester to the rear seat outer belt assembly LH for measurement, as this may lead to a serious injury due to airbag deployment.

      NOTE:
      • Do not forcibly insert SST into the terminals of the connector when connecting SST.
      • Insert SST straight into the terminals of the connector.
      • SST: 09843-18061 
    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.

      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 B1925, B1926, B1927 and B1928 are not output
      DTC B1925, B1926, B1927 or B1928 is output

      HINT: 

      Codes other than DTC B1925, B1926, B1927 and B1928 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. Disconnect SST from connector C.

    Result: 

    DTC B1925, B1926, B1927 and B1928 are not output 

    REPLACE REAR SEAT OUTER BELT ASSEMBLY LH 

    for Fixed Seat Type:

    Refer to REMOVAL [10/2020 - 11/2021] , or refer to REMOVAL [11/2021 - 10/2022] , or refer to REMOVAL [10/2022 - 10/2023]

    for Power Seat:

    Refer to REMOVAL [10/2020 - 11/2021] , or refer to REMOVAL [11/2021 - 10/2022] , or refer to REMOVAL [10/2022 - 10/2023]

    Result: 

    DTC B1925, B1926, B1927 or B1928 is output 

    See step  3

  3. CHECK FLOOR WIRE 
    1. Disconnect the floor wire from the airbag ECU assembly.
      GTY832719Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Outer Belt Assembly LH
      *2 Airbag ECU Assembly
      *3 Floor Wire
      *a Front view of wire harness connector
      (to Rear Seat Outer Belt Assembly LH)
      Release the activation prevention mechanism
    2. Check for a short to B+ in the circuit.
      1. Connect the cable to the negative (-) auxiliary battery terminal.
      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
        L70-1 (RL+) - Body ground Power switch on (IG) Below 1 V
        L70-2 (RL-) - 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.
    3. Check for an open in the circuit.
      1. Measure the resistance according to the value(s) in the table below.

        Standard Resistance

        Tester Connection Condition Specified Condition
        L70-1 (RL+) - L70-2 (RL-) Always Below 1 Ω
    4. Check for a short to ground in the circuit.
      1. Measure the resistance according to the value(s) in the table below.

        Standard Resistance

        Tester Connection Condition Specified Condition
        L70-1 (RL+) - Body ground Always 1 MΩ or higher
        L70-2 (RL-) - Body ground Always 1 MΩ or higher
    5. Check for a short in the circuit.
      1. Release the activation prevention mechanism built into connector B.

        Refer to SYSTEM DESCRIPTION [10/2020 - 10/2023]

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

        Standard Resistance

        Tester Connection Condition Specified Condition
        L70-1 (RL+) - L70-2 (RL-) Always 1 MΩ or higher
      3. Restore the released activation prevention mechanism of connector B to the original condition.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE FLOOR WIRE 

    Result: 

    OK 

    See step  4

  4. CHECK DTC 
    1. Connect the connectors to the rear seat outer belt assembly LH and airbag ECU assembly.
      GTY801379Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Outer Belt Assembly LH
      *2 Airbag ECU Assembly
    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 B1925, B1926, B1927 and B1928 are not output
      DTC B1925, B1926, B1927 or B1928 is output

      HINT: 

      Codes other than DTC B1925, B1926, B1927 and B1928 may be output at this time, but they are not related to this check.

    Result: 

    DTC B1925, B1926, B1927 and B1928 are not output 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2020 - 11/2021]  , or 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 B1925, B1926, B1927 or B1928 is output 

    REPLACE AIRBAG ECU ASSEMBLY. Refer to  REMOVAL [10/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

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