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Home >> Toyota >> 2021 >> Mirai Limited >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> Electronically Controlled Brake System - Diagnostic Codes (4 Of 4), Circuit Tests, Symptom Tests >> Electronically Controlled Brake System >> DTC P0571-12: Brake Switch "A" Circuit Short to Battery [11/2020 - ] >> Procedure

DTC P0571-12: Brake Switch "A" Circuit Short to Battery [11/2020 - ]: Procedure

  1. CHECK BRAKE PEDAL HEIGHT AND STOP LIGHT SWITCH ASSEMBLY INSTALLATION 

    HINT: 

    Refer to ADJUSTMENT [11/2020 - 12/2023] , or refer to ADJUSTMENT [12/2023 - ]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    ADJUST BRAKE PEDAL OR STOP LIGHT SWITCH ASSEMBLY. Refer to  ADJUSTMENT [11/2020 - 12/2023]  , or refer to  ADJUSTMENT [12/2023 - ] 

    Result: 

    OK 

    See step  2

  2. CHECK BRAKE ACTUATOR ASSEMBLY 
    • Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK

      The connector is securely connected.

    Pre-procedure1

    • Disconnect the A6 No. 2 skid control ECU (brake actuator assembly) connector.
    • Check both the connector case and the terminals for deformation and corrosion.

      OK

      No deformation or corrosion.

    • Measure the voltage according to the value(s) in the table below.
      GTY979635Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Stop Light Switch Assembly)

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      A3-2 (L) - Body ground Brake pedal released Below 1.5 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    OK 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [11/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 12/2022]  , or refer to  REMOVAL [12/2022 - 12/2023]  , or refer to  REMOVAL [12/2023 - ] 

    Result: 

    NG 

    See step  3

  3. CHECK NO. 2 SEMICONDUCTOR POWER INTEGRATION ECU 
    • Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK

      The connector is securely connected.

    Pre-procedure1

    • Disconnect the G102 No. 2 semiconductor power integration ECU connector.
    • Check both the connector case and the terminals for deformation and corrosion.

      OK

      No deformation or corrosion.

    • Measure the voltage according to the value(s) in the table below.
      GTY979635Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Stop Light Switch Assembly)

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      A3-2 (L) - Body ground Brake pedal released Below 1.5 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    OK 

    REPLACE NO. 2 SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [11/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 12/2022]  , or refer to  REMOVAL [12/2022 - 12/2023]  , or refer to  REMOVAL [12/2023 - ] 

    Result: 

    NG 

    See step  4

  4. CHECK STOP LIGHT SWITCH ASSEMBLY 
    • Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK

      The connector is securely connected.

    Pre-procedure1

    • Disconnect the A3 stop light switch assembly connector.
    • Check both the connector case and the terminals for deformation and corrosion.

      OK

      No deformation or corrosion.

    • Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      A3-2 (L) - Body ground Always Below 1.5 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    OK 

    REPLACE STOP LIGHT SWITCH ASSEMBLY. Refer to  REMOVAL [11/2020 - 12/2023]  , or refer to  REMOVAL [12/2023 - ] 

    Result: 

    NG 

    See step  5

  5. CHECK FOR SHORT TO +B IN STP CIRCUIT 
    1. Check that there is no short to +B in the STP circuit (wire harnesses, connectors and ECUs).

      OK

      No short to +B.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2020 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE MALFUNCTIONING PART