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Home >> Lexus >> 2021 >> LC 500 2D Coupe >> Repair and Diagnosis >> Restraints >> Air Bag, SRS >> Airbag System - Diagnostic Codes (Coupe) (4 Of 5) >> Airbag System >> DTC B181A/7A: Short in Passenger Side Airbag Variable Vent Hole Squib Circuit; DTC B181B/7A: Open in Passenger Side Airbag Variable Vent Hole Squib Circuit; DTC B181C/7A: Short to GND in Passenger Side Airbag Variable Vent Hole Squib Circuit; DTC B181D/7A: Short to B+ in Passenger Side Airbag Variable Vent Hole Squib Circuit [03/2017 - 04/2020] >> Procedure

DTC B181A/7A: Short in Passenger Side Airbag Variable Vent Hole Squib Circuit; DTC B181B/7A: Open in Passenger Side Airbag Variable Vent Hole Squib Circuit; DTC B181C/7A: Short to GND in Passenger Side Airbag Variable Vent Hole Squib Circuit; DTC B181D/7A: Short to B+ in Passenger Side Airbag Variable Vent Hole Squib Circuit [03/2017 - 04/2020]: Procedure

  1. CHECK CONNECTORS 
    1. Turn the engine switch off.
      GTY779894Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Instrument Panel Passenger Airbag Assembly (Variable Vent Hole Squib)
      *2 Airbag ECU Assembly
      *3 No. 3 Instrument Panel Wire
      *4 Instrument Panel Wire
      *5 Floor Wire
    2. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    3. Check that the connectors are properly connected to the instrument panel passenger airbag assembly (variable vent hole squib), No. 3 instrument panel wire, floor wire 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 instrument panel passenger airbag assembly (variable vent hole squib), No. 3 instrument panel wire, floor wire 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 No. 3 instrument panel wire connector (on the instrument panel passenger airbag assembly side) are not 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 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, INSTRUMENT PANEL WIRE OR NO. 3 INSTRUMENT PANEL WIRE 

    Result: 

    OK 

    See step  2

  2. CHECK INSTRUMENT PANEL PASSENGER AIRBAG ASSEMBLY (VARIABLE VENT HOLE SQUIB) 
    1. Connect the airbag ECU assembly connector.
      GTY837541Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Instrument Panel Passenger Airbag Assembly (Variable Vent Hole Squib)
      *2 Airbag Sensor Assembly
      *3 SST
      *a Front view of wire harness connector
      (to Instrument Panel Passenger Airbag Assembly [Variable Vent Hole Squib])
      *b Color: Green
    2. Connect the white wire side of SST (resistance: 2.1 Ω) to connector G (green connector).
      WARNING:

      Never connect the tester to the instrument panel passenger airbag assembly (variable vent hole squib) 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 (-) battery terminal, and wait for at least 2 seconds.
    4. Turn the engine switch on (IG), and wait for at least 60 seconds.
    5. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [03/2017 - 04/2020]

      Body Electrical > SRS Airbag > Clear DTCs 

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

      Refer to DTC CHECK / CLEAR [03/2017 - 04/2020]

      Body Electrical > SRS Airbag > Trouble Codes 

      Result

      Proceed to
      DTC B181A/7A, B181B/7A, B181C/7A or B181D/7A is not output
      DTC B181A/7A, B181B/7A, B181C/7A or B181D/7A is output

      HINT: 

      Codes other than DTC B181A/7A, B181B/7A, B181C/7A and B181D/7A may be output at this time, but they are not related to this check.

    9. Turn the engine switch off.
    10. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 seconds.
    11. Disconnect SST from connector G.

    Result: 

    DTC B181A/7A, B181B/7A, B181C/7A or B181D/7A is not output 

    REPLACE INSTRUMENT PANEL PASSENGER AIRBAG ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

    Result: 

    DTC B181A/7A, B181B/7A, B181C/7A or B181D/7A is output 

    See step  3

  3. CHECK VARIABLE VENT HOLE SQUIB CIRCUIT 
    1. Disconnect the floor wire from the airbag ECU assembly.
      GTY779701Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Instrument Panel Passenger Airbag Assembly (Variable Vent Hole Squib)
      *2 Airbag ECU Assembly
      *3 No. 3 Instrument Panel Wire
      *4 Instrument Panel Wire
      *5 Floor Wire
      *a Front view of wire harness connector
      (to Instrument Panel Passenger Airbag Assembly [Variable Vent Hole Squib])
      *b Color: Orange
      Release the activation prevention mechanism
    2. Check for a short to B+ in the circuit.
      1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
      2. Turn the engine switch on (IG).
      3. Measure the voltage according to the value(s) in the table below.

        Standard Voltage

        Tester Connection Switch Condition Specified Condition
        B3-1 (VHP-) - Body ground Engine switch on (IG) Below 1 V
        B3-2 (VHP+) - Body ground Engine switch on (IG) Below 1 V
      4. Turn the engine switch off.
      5. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 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
        B3-1 (VHP-) - B3-2 (VHP+) 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
        B3-1 (VHP-) - Body ground Always 1 MΩ or higher
        B3-2 (VHP+) - 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 [03/2017 - ]

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

        Standard Resistance

        Tester Connection Condition Specified Condition
        B3-1 (VHP-) - B3-2 (VHP+) 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 instrument panel passenger airbag assembly and airbag ECU assembly.
      GTY782870Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Instrument Panel Passenger Airbag Assembly (Variable Vent Hole Squib)
      *2 Airbag Sensor Assembly
    2. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
    3. Turn the engine switch on (IG), and wait for at least 60 seconds.
    4. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [03/2017 - 04/2020]

      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.

      Refer to DTC CHECK / CLEAR [03/2017 - 04/2020]

      Body Electrical > SRS Airbag > Trouble Codes 

      Result

      Proceed to
      DTC B181A/7A, B181B/7A, B181C/7A or B181D/7A is output
      DTC B181A/7A, B181B/7A, B181C/7A or B181D/7A is not output

      HINT: 

      Codes other than DTC B181A/7A, B181B/7A, B181C/7A and B181D/7A may be output at this time, but they are not related to this check.

    Result: 

    DTC B181A/7A, B181B/7A, B181C/7A or B181D/7A is output 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [03/2017 - 04/2020] 

    Result: 

    DTC B181A/7A, B181B/7A, B181C/7A or B181D/7A is not output 

    REPLACE AIRBAG ECU ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023] 

  5. CHECK VARIABLE VENT HOLE SQUIB CIRCUIT 
    1. Disconnect the instrument panel wire connector from the No. 3 instrument panel wire.
      GTY786505Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Instrument Panel Passenger Airbag Assembly (Variable Vent Hole Squib)
      *2 Airbag ECU Assembly
      *3 No. 3 Instrument Panel Wire
      *4 Instrument Panel Wire
      *5 Floor Wire
      *a Front view of wire harness connector
      (to No. 3 Instrument Panel Wire)
      Release the activation prevention mechanism
    2. Check for a short to B+ in the circuit.
      1. Connect the cable to the negative (-) battery terminal, and wait for at least 2 seconds.
      2. Turn the engine switch on (IG).
      3. Measure the voltage according to the value(s) in the table below.

        Standard Voltage

        Tester Connection Switch Condition Specified Condition
        PB1-1 (VHP+) - Body ground Engine switch on (IG) Below 1 V
        PB1-2 (VHP-) - Body ground Engine switch on (IG) Below 1 V
      4. Turn the engine switch off.
      5. Disconnect the cable from the negative (-) battery terminal, and wait for at least 90 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
        PB1-1 (VHP+) - PB1-2 (VHP-) 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
        PB1-1 (VHP+) - Body ground Always 1 MΩ or higher
        PB1-2 (VHP-) - 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 [03/2017 - ]

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

        Standard Resistance

        Tester Connection Condition Specified Condition
        PB1-1 (VHP+) - PB1-2 (VHP-) 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 NO. 3 INSTRUMENT PANEL WIRE 

    Result: 

    NG 

    See step  6

  6. CHECK FLOOR WIRE 
    1. Disconnect the floor wire connector from the instrument panel wire.
      GTY793219Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Instrument Panel Passenger Airbag Assembly (Variable Vent Hole Squib)
      *2 Airbag ECU Assembly
      *3 No. 3 Instrument Panel Wire
      *4 Instrument Panel Wire
      *5 Floor Wire
      *a Front view of wire harness connector
      (to Instrument Panel Wire)
      Release the activation prevention mechanism
    2. 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
        XP1-1 (VHP+) - XP1-2 (VHP-) Always Below 1 Ω
    3. 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
        XP1-1 (VHP+) - Body ground Always 1 MΩ or higher
        XP1-2 (VHP-) - Body ground Always 1 MΩ or higher
    4. Check for a short in the circuit.
      1. Release the activation prevention mechanism built into connector B.

        Refer to SYSTEM DESCRIPTION [03/2017 - ]

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

        Standard Resistance

        Tester Connection Condition Specified Condition
        XP1-1 (VHP+) - XP1-2 (VHP-) 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 INSTRUMENT PANEL WIRE 

    Result: 

    NG 

    REPLACE FLOOR WIRE 

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