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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 B1850: Short in Rear Side Squib RH Circuit; DTC B1851: Open in Rear Side Squib RH Circuit; DTC B1852: Short to GND in Rear Side Squib RH Circuit; DTC B1853: Short to B+ in Rear Side Squib RH Circuit [10/2020 - 10/2023] >> Procedure

DTC B1850: Short in Rear Side Squib RH Circuit; DTC B1851: Open in Rear Side Squib RH Circuit; DTC B1852: Short to GND in Rear Side Squib RH Circuit; DTC B1853: Short to B+ in Rear Side Squib RH Circuit [10/2020 - 10/2023]: Procedure

  1. CHECK VEHICLE CONDITION 
    1. Check vehicle condition.

      Result

      Proceed to
      for Fixed Seat Type
      for Power Seat

    Result: 

    for Power Seat 

    See step  6

    Result: 

    for Fixed Seat Type 

    See step  2

  2. CHECK CONNECTORS 
    1. Turn the power switch off.
      GTY751176Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly RH
      *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 airbag assembly RH 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 airbag assembly RH 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 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  3

  3. CHECK REAR SEAT AIRBAG ASSEMBLY RH 
    1. Connect the connector to the airbag ECU assembly.
      GTY808229Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly RH
      *2 Airbag ECU Assembly
      *3 SST
      *a Front view of wire harness connector
      (to Rear Seat Airbag Assembly RH)
    2. Connect the red wire side of SST (resistance: 2.1 Ω) to connector C.
      WARNING:

      Never connect the tester to the rear seat airbag assembly RH 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 B1850, B1851, B1852 and B1853 are not output.
      DTC B1850, B1851, B1852 or B1853 is output.

      HINT: 

      Codes other than DTC B1850, B1851, B1852 and B1853 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 B1850, B1851, B1852 and B1853 are not output. 

    REPLACE REAR SEAT AIRBAG ASSEMBLY RH. 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 B1850, B1851, B1852 or B1853 is output. 

    See step  4

  4. CHECK FLOOR WIRE 
    1. Disconnect the floor wire from the airbag ECU assembly.
      GTY821770Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly RH
      *2 Airbag ECU Assembly
      *3 Floor Wire
      *a Front view of wire harness connector
      (to Rear Seat Airbag Assembly RH)
      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, and wait for at least 2 seconds.
      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
        L106-1 (SRR+) - Body ground Power switch on (IG) Below 1 V
        L106-2 (SRR-) - 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
        L106-1 (SRR+) - L106-2 (SRR-) 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
        L106-1 (SRR+) - Body ground Always 1 MΩ or higher
        L106-2 (SRR-) - Body ground Always 1 MΩ or higher
    5. Check for a short in the circuit.

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

      1. Release the activation prevention mechanism built into connector B.
      2. Measure the resistance according to the value(s) in the table below.

        Standard Resistance

        Tester Connection Condition Specified Condition
        L106-1 (SRR+) - L106-2 (SRR-) 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  5

  5. CHECK DTC 
    1. Connect the connectors to the rear seat airbag assembly RH and airbag ECU assembly.
      GTY788309Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly RH
      *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 B1850, B1851, B1852 and B1853 are not output
      DTC B1850, B1851, B1852 or B1853 is output

      HINT: 

      Codes other than DTC B1850, B1851, B1852 and B1853 may be output at this time, but they are not related to this check.

    Result: 

    DTC B1850, B1851, B1852 and B1853 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 B1850, B1851, B1852 or B1853 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] 

  6. CHECK CONNECTORS 
    1. Turn the power switch off.
      GTY794190Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly RH
      *2 Airbag ECU Assembly
      *3 Rear Seat Wire RH
      *4 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 airbag assembly RH 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 airbag assembly RH 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 short springs of the activation prevention mechanism of the rear seat airbag assembly RH connector and rear seat wire connector are not deformed or damaged.

      OK

      The short springs are not deformed or damaged.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE REAR SEAT WIRE RH OR FLOOR WIRE 

    Result: 

    OK 

    See step  7

  7. CHECK REAR SEAT AIRBAG ASSEMBLY RH 
    1. Connect the connector to the airbag ECU assembly.
      GTY823496Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly RH
      *2 Airbag ECU Assembly
      *3 SST
      *a Front view of wire harness connector
      (to Rear Seat Airbag Assembly RH)
    2. Connect the red wire side of SST (resistance: 2.1 Ω) to connector E.
      WARNING:

      Never connect the tester to the rear seat airbag assembly RH 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 B1850, B1851, B1852 and B1853 are not output.
      DTC B1850, B1851, B1852 or B1853 is output.

      HINT: 

      Codes other than DTC B1850, B1851, B1852 and B1853 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 E.

    Result: 

    DTC B1850, B1851, B1852 and B1853 are not output. 

    REPLACE REAR SEAT AIRBAG ASSEMBLY RH. 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 B1850, B1851, B1852 or B1853 is output. 

    See step  8

  8. CHECK REAR SEAT AIRBAG ASSEMBLY RH CIRCUIT 
    1. Disconnect the floor wire from the airbag ECU assembly.
      GTY830231Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly RH
      *2 Airbag ECU Assembly
      *3 Rear Seat Wire RH
      *4 Floor Wire
      *a Front view of wire harness connector
      (to Rear Seat Airbag Assembly RH)
      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, and wait for at least 2 seconds.
      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
        R16-1 (SRR+) - Body ground Power switch on (IG) Below 1 V
        R16-2 (SRR-) - 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
        R16-1 (SRR+) - R16-2 (SRR-) 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
        R16-1 (SRR+) - Body ground Always 1 MΩ or higher
        R16-2 (SRR-) - Body ground Always 1 MΩ or higher
    5. Check for a short in the circuit.

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

      1. Release the activation prevention mechanism built into connector B.
      2. Measure the resistance according to the value(s) in the table below.

        Standard Resistance

        Tester Connection Condition Specified Condition
        R16-1 (SRR+) - R16-2 (SRR-) 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 

    See step  10

    Result: 

    OK 

    See step  9

  9. CHECK DTC 
    1. Connect the connectors to the rear seat airbag assembly RH and airbag ECU assembly.
      GTY820609Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly RH
      *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 B1850, B1851, B1852 and B1853 are not output
      DTC B1850, B1851, B1852 or B1853 is output

      HINT: 

      Codes other than DTC B1850, B1851, B1852 and B1853 may be output at this time, but they are not related to this check.

    Result: 

    DTC B1850, B1851, B1852 and B1853 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 B1850, B1851, B1852 or B1853 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] 

  10. CHECK FLOOR WIRE 
    1. Disconnect the floor wire from the airbag ECU assembly.
      GTY778399Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly RH
      *2 Airbag ECU Assembly
      *3 Rear Seat Wire RH
      *4 Floor Wire
      *a Front view of wire harness connector
      (to Rear Seat Airbag Assembly RH)
      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, and wait for at least 2 seconds.
      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
        LR 9-1 (SRR+) - Body ground Power switch on (IG) Below 1 V
        LR 9-2 (SRR-) - 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
        LR 9-1 (SRR+) - LR 9-2 (SRR-) 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
        LR 9-1 (SRR+) - Body ground Always 1 MΩ or higher
        LR 9-2 (SRR-) - Body ground Always 1 MΩ or higher
    5. Check for a short in the circuit.

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

      1. Release the activation prevention mechanism built into connector B.
      2. Measure the resistance according to the value(s) in the table below.

        Standard Resistance

        Tester Connection Condition Specified Condition
        LR 9-1 (SRR+) - LR 9-2 (SRR-) 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: 

    OK 

    REPLACE REAR SEAT WIRE RH 

    Result: 

    NG 

    REPLACE FLOOR WIRE 

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