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Home >> Toyota >> 2020 >> Prius Limited >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Supplemental Restraint System - Diagnostic Codes (5 Of 5) & Symptom Tests >> Airbag System >> 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 [07/2020 - ] >> 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 [07/2020 - ]: Procedure

  1. CHECK CONNECTORS 
    1. Turn the power switch off.
      GTY1018667Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly LH
      *2 Airbag ECU Assembly
      *3 Wire Harness
      *4 Floor Wire
    2. Disconnect the cable from the negative (-) auxiliary battery terminal.
      WARNING:

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

    3. Check that the connectors are properly connected to the rear seat airbag assembly LH and airbag ECU assembly. Also check that the connectors that link the floor wire and wire harness are properly connected.

      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. Also disconnect the floor wire from the wire harness.
    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 wire harness connector (on the rear seat airbag assembly LH side) is not loose, deformed or damaged.

      OK

      The airbag 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

      Result Proceed to
      OK A
      NG (Floor Wire) B
      NG (Wire Harness) C

    Result: 

    B 

    REPLACE FLOOR WIRE 

    Result: 

    C 

    REPLACE REAR SEAT AIRBAG ASSEMBLY LH. Refer to  REMOVAL [07/2020 - ] 

    Result: 

    A 

    See step  2

  2. CHECK REAR SEAT AIRBAG ASSEMBLY LH 
    1. Connect the floor wire to the wire harness and airbag ECU assembly.
      GTY1014085Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly LH
      *2 Airbag ECU Assembly
      *a Front view of wire harness connector
      (to Rear Seat Airbag Assembly LH)
    2. Connect SST (resistance 2.1 Ω) to connector E.
      WARNING:

      Never connect a 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 it.
      • Insert SST straight into the terminals of the connector.
      • SST: 09843-18061 
    3. Connect the cable to the negative (-) auxiliary battery terminal.
    4. Turn the power switch on (IG), and wait for at least 60 seconds.
    5. Clear the DTCs stored in memory.

      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.

      Body Electrical > SRS Airbag > Trouble Codes 

      OK

      DTC B1855, B1856, B1857 or B1858 is not output.

      HINT: 

      Codes other than DTCs 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.
      WARNING:

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

    11. Disconnect SST from connector E.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE REAR SEAT AIRBAG ASSEMBLY LH. Refer to  REMOVAL [07/2020 - ] 

    Result: 

    NG 

    See step  3

  3. CHECK WIRE HARNESS (AIRBAG ECU ASSEMBLY - REAR SEAT AIRBAG ASSEMBLY LH) 
    1. Disconnect the floor wire from the airbag ECU assembly.
      GTY1013593Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly LH
      *2 Airbag ECU Assembly
      *3 Wire Harness
      *4 Floor Wire
      *a Front view of wire harness connector
      (to Rear Seat Airbag Assembly LH)
    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 Condition Specified Condition
        E-2 (SRL+) - Body ground Power switch on (IG) Below 1 V
        E-1 (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.
        WARNING:

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

    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
        E-2 (SRL+) - E-1 (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
        E-2 (SRL+) - Body ground Always 1 MΩ or higher
        E-1 (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 [07/2020 - ]

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

        Standard Resistance

        Tester Connection Condition Specified Condition
        E-2 (SRL+) - E-1 (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  5

    Result: 

    OK 

    See step  4

  4. CHECK DTC 
    1. Connect the connectors to the rear seat airbag assembly LH and airbag ECU assembly.
      GTY1018629Courtesy 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.
    3. Turn the power 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 power switch off.
    6. Turn the power switch on (IG), and wait for at least 60 seconds.
    7. Check for DTCs.

      Body Electrical > SRS Airbag > Trouble Codes 

      OK

      DTC B1855, B1856, B1857 or B1858 is not output.

      HINT: 

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

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [07/2020 - 06/2021]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [06/2021 - ] 

    Result: 

    NG 

    REPLACE AIRBAG ECU ASSEMBLY. Refer to  REMOVAL [07/2020 - ] 

  5. CHECK FLOOR WIRE 
    1. Disconnect the wire harness from the floor wire.
      GTY1014246Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Rear Seat Airbag Assembly LH
      *2 Airbag ECU Assembly
      *3 Wire Harness
      *4 Floor Wire
      *a Front view of wire harness connector
      (to Wire Harness)
    2. Release the activation prevention mechanism built into connector C.

      Refer to SYSTEM DESCRIPTION [07/2020 - ]

    3. 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

        (M105)

        (M105)

        Tester Connection Condition Specified Condition
        M105-2 (SRL+) - Body ground Power switch on (IG) Below 1 V
        M105-1 (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.
        WARNING:

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

    4. Check for an open in the circuit.
      1. Measure the resistance according to the value(s) in the table below.

        Standard Resistance

        (M105)

        (M105)

        Tester Connection Condition Specified Condition
        M105-2 (SRL+) - M105-1 (SRL-) Always Below 1 Ω
    5. Check for a short to ground in the circuit.
      1. Measure the resistance according to the value(s) in the table below.

        Standard Resistance

        (M105)

        (M105)

        Tester Connection Condition Specified Condition
        M105-2 (SRL+) - Body ground Always 1 MΩ or higher
        M105-1 (SRL-) - Body ground Always 1 MΩ or higher
    6. Check for a short in the circuit.
      1. Release the activation prevention mechanism built into connector B.

        Refer to SYSTEM DESCRIPTION [07/2020 - ]

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

        Standard Resistance

        (M105)

        (M105)

        Tester Connection Condition Specified Condition
        M105-2 (SRL+) - M105-1 (SRL-) Always 1 MΩ or higher
      3. Restore the released activation prevention mechanism of connector B to the original condition.
    7. Restore the released activation prevention mechanism of connector C to the original condition.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE REAR SEAT AIRBAG ASSEMBLY LH. Refer to  REMOVAL [07/2020 - ] 

    Result: 

    NG 

    REPLACE FLOOR WIRE 

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