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Home >> Lexus >> 2021 >> ES 350 Base >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> Electronically Controlled Brake System (Except Hybrid) - Diagnostic Codes (4 Of 4) & Symptom Tests >> ELECTRONICALLY CONTROLLED BRAKE SYSTEM (for Gasoline Model) >> DTC P0571-12: Brake Switch "A" Circuit Short to Battery [06/2018 - 08/2020] >> Procedure

DTC P0571-12: Brake Switch "A" Circuit Short to Battery [06/2018 - 08/2020]: Procedure

  1. CHECK BRAKE PEDAL OR STOP LIGHT SWITCH ASSEMBLY INSTALLATION 
    1. Check the brake pedal height and stop light switch assembly installation.

      Refer to ADJUSTMENT [06/2018 - 08/2020]

      OK

      The brake pedal height and stop light switch assembly installation are normal.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    ADJUST BRAKE PEDAL OR STOP LIGHT SWITCH ASSEMBLY. Refer to  ADJUSTMENT [06/2018 - 08/2020] 

    Result: 

    OK 

    See step  2

  2. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY OUTPUT CIRCUIT) 
    1. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK

      The connector is securely connected.

      GTY804297Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Stop Light Switch Assembly)
    2. Disconnect the A40 skid control ECU (brake actuator assembly) connector.
    3. Check both the connector case and the terminals for deformation and corrosion.

      OK

      No deformation or corrosion.

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

      Standard Voltage

      Tester Connection Condition Specified Condition
      A43-3 (L) - Body ground Brake pedal released Below 1.5 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [06/2018 - 08/2020] 

    Result: 

    NG 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BRAKE ACTUATOR ASSEMBLY) 
    1. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK

      The connector is securely connected.

      GTY810610Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Stop Light Switch Assembly)
    2. Disconnect the A40 skid control ECU (brake actuator assembly) connector.
    3. Disconnect the A43 stop light switch assembly connector.
    4. Check both the connector case and the terminals for deformation and corrosion.

      OK

      No deformation or corrosion.

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

      Standard Voltage

      Tester Connection Condition Specified Condition
      A43-3 (L) - Body ground Always Below 1.5 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE STOP LIGHT SWITCH ASSEMBLY. Refer to  REMOVAL [06/2018 - ] 

    Result: 

    NG 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - ECM) 
    1. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK

      The connector is securely connected.

      GTY810610Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Stop Light Switch Assembly)
    2. Disconnect the A40 skid control ECU (brake actuator assembly) connector.
    3. Disconnect the A43 stop light switch assembly connector.
    4. Disconnect the A25 ECM connector.
    5. Check both the connector case and the terminals for deformation and corrosion.

      OK

      No deformation or corrosion.

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

      Standard Voltage

      Tester Connection Condition Specified Condition
      A43-3 (L) - Body ground Always Below 1.5 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE ECM. Refer to  REMOVAL [06/2018 - 10/2019]  , or refer to  REMOVAL [10/2019 - 08/2021] 

    Result: 

    NG 

    See step  5

  5. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - SHIFT LOCK CONTROL UNIT ASSEMBLY) 
    1. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK

      The connector is securely connected.

      GTY810610Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Stop Light Switch Assembly)
    2. Disconnect the A40 skid control ECU (brake actuator assembly) connector.
    3. Disconnect the A43 stop light switch assembly connector.
    4. Disconnect the A25 ECM connector.
    5. Disconnect the G25 shift lock control ECU (shift lock control unit assembly) connector.
    6. Check both the connector case and the terminals for deformation and corrosion.

      OK

      No deformation or corrosion.

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

      Standard Voltage

      Tester Connection Condition Specified Condition
      A43-3 (L) - Body ground Always Below 1.5 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SHIFT LOCK CONTROL UNIT ASSEMBLY. Refer to  REMOVAL [06/2018 - 09/2022] 

    Result: 

    NG 

    See step  6

  6. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - SMART KEY ECU ASSEMBLY) 
    1. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK

      The connector is securely connected.

      GTY810610Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Front view of wire harness connector
      (to Stop Light Switch Assembly)
    2. Disconnect the A40 skid control ECU (brake actuator assembly) connector.
    3. Disconnect the A43 stop light switch assembly connector.
    4. Disconnect the A25 ECM connector.
    5. Disconnect the G25 shift lock control ECU (shift lock control unit assembly) connector.
    6. Disconnect the N9 certification ECU (smart key ECU assembly) connector.
    7. Check both the connector case and the terminals for deformation and corrosion.

      OK

      No deformation or corrosion.

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

      Standard Voltage

      Tester Connection Condition Specified Condition
      A43-3 (L) - Body ground Always Below 1.5 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SMART KEY ECU ASSEMBLY. Refer to  REMOVAL [06/2018 - 08/2021] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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