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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 B1800: Short in Driver Squib Circuit; DTC B1801: Open in Driver Squib Circuit; DTC B1802: Short to GND in Driver Side Squib Circuit; DTC B1803: Short to B+ in Driver Side Squib Circuit [10/2020 - 10/2023] >> Procedure

DTC B1800: Short in Driver Squib Circuit; DTC B1801: Open in Driver Squib Circuit; DTC B1802: Short to GND in Driver Side Squib Circuit; DTC B1803: Short to B+ in Driver Side Squib Circuit [10/2020 - 10/2023]: Procedure

  1. CHECK CONNECTORS 
    1. Turn the power switch off.
      GTY771429Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Horn Button Assembly
      *2 Airbag ECU Assembly
      *3 Spiral Cable Sub-assembly
      *4 Instrument Panel 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 horn button assembly, spiral cable sub-assembly 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 horn button assembly, spiral cable sub-assembly 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 spiral cable sub-assembly connector (on the horn button assembly 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 mechanisms of the instrument panel wire connector and spiral cable sub-assembly connector are not deformed or damaged.

      OK

      The short springs are not deformed or damaged.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE INSTRUMENT PANEL WIRE OR SPIRAL CABLE SUB-ASSEMBLY 

    Result: 

    OK 

    See step  2

  2. CHECK HORN BUTTON ASSEMBLY 
    1. Connect the instrument panel wire to the airbag ECU assembly and spiral cable sub-assembly.
      GTY789710Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Horn Button Assembly
      *2 Airbag ECU Assembly
      *3 Spiral Cable Sub-assembly
      *4 SST
      *a Front view of wire harness connector
      (to Horn Button Assembly)
      *b Color: Light Green
    2. Connect the white wire side of SST (resistance: 2.1 Ω) to connector E (light green connector).
      WARNING:

      Never connect the tester to the horn button assembly 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 B1800, B1801, B1802 and B1803 are not output
      DTC B1800, B1801, B1802 or B1803 is output

      HINT: 

      Codes other than DTC B1800, B1801, B1802 and B1803 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 B1800, B1801, B1802 and B1803 are not output 

    REPLACE HORN BUTTON ASSEMBLY. 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 B1800, B1801, B1802 or B1803 is output 

    See step  3

  3. CHECK DRIVER SIDE SQUIB CIRCUIT 
    1. Disconnect the instrument panel wire from the airbag ECU assembly.
      GTY835989Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Horn Button Assembly
      *2 Airbag ECU Assembly
      *3 Spiral Cable Sub-assembly
      *a Front view of wire harness connector
      (to Horn Button Assembly)
      *b Color: Light Green
      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 Switch Condition Specified Condition
        z3-2 (D+) - Body ground Power switch on (IG) Below 1 V
        z3-1 (D-) - 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
        z3-2 (D+) - z3-1 (D-) 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
        z3-2 (D+) - Body ground Always 1 MΩ or higher
        z3-1 (D-) - 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
        z3-2 (D+) - z3-1 (D-) Always 1 MΩ or higher
      3. Restore the released activation prevention mechanism of connector B to its 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 horn button assembly and airbag ECU assembly.
      GTY782188Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Horn Button Assembly
      *2 Airbag ECU Assembly
      *3 Spiral Cable Sub-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 B1800, B1801, B1802 and B1803 are not output
      DTC B1800, B1801, B1802 or B1803 is output

      HINT: 

      Codes other than DTC B1800, B1801, B1802 and B1803 may be output at this time, but they are not related to this check.

    Result: 

    DTC B1800, B1801, B1802 and B1803 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 B1800, B1801, B1802 or B1803 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] 

  5. CHECK INSTRUMENT PANEL WIRE 
    1. Disconnect the instrument panel wire from the spiral cable sub-assembly.
      GTY788380Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *1 Horn Button Assembly
      *2 Airbag ECU Assembly
      *3 Spiral Cable Sub-assembly
      *4 Instrument Panel Wire
      *a Front view of wire harness connector
      (to Spiral Cable Sub-assembly)
      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
        G 26-1 (D+) - Body ground Power switch on (IG) Below 1 V
        G 26-2 (D-) - 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
        G 26-1 (D+) - G 26-2 (D-) 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
        G 26-1 (D+) - Body ground Always 1 MΩ or higher
        G 26-2 (D-) - 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
        G 26-1 (D+) - G 26-2 (D-) 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 SPIRAL CABLE SUB-ASSEMBLY. Refer to  REMOVAL [10/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

    Result: 

    NG 

    REPLACE INSTRUMENT PANEL WIRE 

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