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Home >> Lexus >> 2022 >> 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 B1855: Short in Rear Side Squib LH Circuit; DTC B1856: Open in Rear Side Squib LH Circuit; DTC B1857: Short to GND in Rear Side Squib LH Circuit; DTC B1858: Short to B+ in Rear Side Squib LH Circuit [10/2020 - 10/2023] >> Procedure

DTC B1855: Short in Rear Side Squib LH Circuit; DTC B1856: Open in Rear Side Squib LH Circuit; DTC B1857: Short to GND in Rear Side Squib LH Circuit; DTC B1858: Short to B+ in Rear Side Squib LH 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.
      GTY760543Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag 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 airbag 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 airbag 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 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 LH 
    1. Connect the connector to the airbag ECU assembly.
      GTY832768Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly LH
      *2 Airbag ECU Assembly
      *3 SST
      *a Front view of wire harness connector
      (to Rear Seat Airbag Assembly LH)
    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 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 B1855, B1856, B1857 and B1858 are not output.
      DTC B1855, B1856, B1857 or B1858 is output.

      HINT: 

      Codes other than DTC B1855, B1856, B1857 and B1858 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 B1855, B1856, B1857 and B1858 are not output. 

    REPLACE REAR SEAT AIRBAG ASSEMBLY LH. 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 B1855, B1856, B1857 or B1858 is output. 

    See step  4

  4. CHECK FLOOR WIRE 
    1. Disconnect the floor wire from the airbag ECU assembly.
      GTY785991Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly LH
      *2 Airbag ECU Assembly
      *3 Floor Wire
      *a Front view of wire harness connector
      (to Rear Seat Airbag 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, 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
        L107-1 (SRL+) - Body ground Power switch on (IG) Below 1 V
        L107-2 (SRL-) - 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
        L107-1 (SRL+) - L107-2 (SRL-) 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
        L107-1 (SRL+) - Body ground Always 1 MΩ or higher
        L107-2 (SRL-) - 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
        L107-1 (SRL+) - L107-2 (SRL-) 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 LH and airbag ECU assembly.
      GTY801387Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag 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 B1855, B1856, B1857 and B1858 are not output
      DTC B1855, B1856, B1857 or B1858 is output

      HINT: 

      Codes other than DTC B1855, B1856, B1857 and B1858 may be output at this time, but they are not related to this check.

    Result: 

    DTC B1855, B1856, B1857 and B1858 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 B1855, B1856, B1857 or B1858 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.
      GTY797819Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly LH
      *2 Airbag ECU Assembly
      *3 Rear Seat Wire LH
      *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 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 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 wire connector and rear seat airbag assembly LH 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 LH OR FLOOR WIRE 

    Result: 

    OK 

    See step  7

  7. CHECK REAR SEAT AIRBAG ASSEMBLY LH 
    1. Connect the connector to the airbag ECU assembly.
      GTY817471Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly LH
      *2 Airbag ECU Assembly
      *3 SST
      *a Front view of wire harness connector
      (to Rear Seat Airbag Assembly LH)
    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 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 B1855, B1856, B1857 and B1858 are not output.
      DTC B1855, B1856, B1857 or B1858 is output.

      HINT: 

      Codes other than DTC B1855, B1856, B1857 and B1858 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 B1855, B1856, B1857 and B1858 are not output. 

    REPLACE REAR SEAT AIRBAG ASSEMBLY LH. 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 B1855, B1856, B1857 or B1858 is output. 

    See step  8

  8. CHECK REAR SEAT AIRBAG ASSEMBLY LH CIRCUIT 
    1. Disconnect the floor wire from the airbag ECU assembly.
      GTY831059Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly LH
      *2 Airbag ECU Assembly
      *3 Rear Seat Wire LH
      *4 Floor Wire
      *a Front view of wire harness connector
      (to Rear Seat Airbag 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, 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
        R51-1 (SRL+) - Body ground Power switch on (IG) Below 1 V
        R51-2 (SRL-) - 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
        R51-1 (SRL+) - R51-2 (SRL-) 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
        R51-1 (SRL+) - Body ground Always 1 MΩ or higher
        R51-2 (SRL-) - 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
        R51-1 (SRL+) - R51-2 (SRL-) 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 LH and airbag ECU assembly.
      GTY837377Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag 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 B1855, B1856, B1857 and B1858 are not output
      DTC B1855, B1856, B1857 or B1858 is output

      HINT: 

      Codes other than DTC B1855, B1856, B1857 and B1858 may be output at this time, but they are not related to this check.

    Result: 

    DTC B1855, B1856, B1857 and B1858 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 B1855, B1856, B1857 or B1858 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.
      GTY817712Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly LH
      *2 Airbag ECU Assembly
      *3 Floor Wire
      *4 Rear Seat Wire LH
      *a Front view of wire harness connector
      (to Rear Seat Airbag 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, 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 10-1 (SRL+) - Body ground Power switch on (IG) Below 1 V
        LR 10-2 (SRL-) - 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 10-1 (SRL+) - LR 10-2 (SRL-) 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 10-1 (SRL+) - Body ground Always 1 MΩ or higher
        LR 10-2 (SRL-) - 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
        LR 10-1 (SRL+) - LR 10-2 (SRL-) 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 LH 

    Result: 

    NG 

    REPLACE FLOOR WIRE 

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