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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 P0571-13: Brake Switch "A" Circuit Open [12/2023 - ] >> Procedure

DTC P0571-13: Brake Switch "A" Circuit Open [12/2023 - ]: Procedure

  1. CHECK VEHICLE 

    Result

    Result Proceed to
    w/ Front LiDAR Sensor A
    w/o Front LiDAR Sensor B

    Result: 

    B 

    See step  14

    Result: 

    A 

    See step  2

  2. CHECK STOP LIGHT OPERATION 
    1. Check that the stop lights come on when the brake pedal is depressed.

      Result

      Result Proceed to
      All stop lights illuminate when the brake pedal is depressed and turn off when the brake pedal is released. A
      All stop lights do not illuminate when the brake pedal is depressed. B
      One or more stop lights illuminate when the brake pedal is depressed but remain on when the brake pedal is released. C

    Result: 

    B 

    See step  12

    Result: 

    C 

    See step  7

    Result: 

    A 

    See step  3

  3. READ VALUE USING GTS (STOP LIGHT SWITCH ASSEMBLY) 
    1. Check the value of Stop Light SW when the brake pedal is depressed.

      Chassis > Brake/EPB > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Stop Light SW Stop light switch assembly status
      (STP or STP2 terminal input)      		 OFF / ON OFF: Brake pedal released
      ON: Brake pedal depressed      		 HINT: 
      • Stop light control relay off: STP terminal status displayed.
      • Stop light control relay on: STP2 terminal status displayed.

      Chassis > Brake/EPB > Data List 

      Tester Display
      Stop Light SW

      Result

      Result Proceed to
      The value of Stop Light SW is ON A
      None of the above conditions are met B

    Result: 

    B 

    See step  9

    Result: 

    A 

    See step  4

  4. STOP LIGHT SWITCH ASSEMBLY OUTPUT CIRCUIT INSPECTION 

    Pre-procedure1

    • Turn the ignition switch off.
    • 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-procedure2

    • Turn the ignition switch to ON.
    • 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
      • Ignition switch ON
      • The headlights are on
      • The blower motor switch is in the HI position
      • The rear window defogger is turned on
      • Stop light switch assembly off (Brake pedal released)
      		 Below 1.5 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    NG 

    See step  7

    Result: 

    OK 

    See step  5

  5. CLEAR DTC 

    Pre-procedure1

    • None
    • Clear the DTCs.

      Chassis > Brake/EPB > Clear DTCs 

      Result

      Proceed to
      NEXT

    Post-procedure1

    • Turn the ignition switch off.

    Result: 

    NEXT 

    See step  6

  6. RECONFIRM DTC 

    Pre-procedure1

    • Based on the Freeze Frame Data and interview with the customer, attempt to reproduce the conditions when the malfunction occurred.
    • Check if the same DTC is output.

      Chassis > Brake/EPB > Trouble Codes 

      Result

      Result Proceed to
      P0571-13 is not output A
      P0571-13 is output B

    Post-procedure1

    • None

    Result: 

    A 

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

    Result: 

    B 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [12/2023 - ] 

  7. CHECK STOP LIGHT SWITCH ASSEMBLY 

    Pre-procedure1

    • Turn the ignition switch off.
    • 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-procedure2

    • 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 Stop light switch assembly off
      (Brake pedal released)      		 Below 1.5 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    OK 

    REPLACE STOP LIGHT SWITCH ASSEMBLY. Refer to  REMOVAL [12/2023 - ] 

    Result: 

    NG 

    See step  8

  8. 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.

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      A3-2 (L) - Body ground Stop light switch assembly off
      (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 [12/2023 - ] 

    Result: 

    NG 

    See step  10

  9. CHECK HARNESS AND CONNECTOR (STP TERMINAL) 

    Pre-procedure1

    • Turn the ignition switch off.
    • 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-procedure2

    • 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.

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      A3-2 (L) - Body ground Stop light switch assembly on
      (Brake pedal depressed)      		 11 to 14 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    OK 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [12/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  10. 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.

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      A3-2 (L) - Body ground Stop light switch assembly off
      (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 [12/2023 - ] 

    Result: 

    NG 

    See step  11

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

      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 

  12. CHECK NO. 2 SEMICONDUCTOR POWER INTEGRATION ECU 
    1. Make sure that there is no looseness at the locking part and the connecting part of the connectors.

      OK

      The connector is securely connected.

    2. Measure the voltage according to the value(s) in the table below.
      GTY972375Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (No. 2 Semiconductor Power Integration ECU)

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      G102-10 (STP) - Body ground Stop light switch assembly on
      (Brake pedal depressed)      		 11 to 14 V V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE NO. 2 SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [12/2023 - ] 

    Result: 

    NG 

    See step  13

  13. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - NO. 2 SEMICONDUCTOR POWER INTEGRATION ECU) 
    1. Check that there is no open in the wire harnesses and connectors from terminal L of the stop light switch assembly to the No. 2 semiconductor power integration ECU.

      OK

      No open.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [12/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  14. CHECK STOP LIGHT OPERATION 
    1. Check that the stop lights come on when the brake pedal is depressed.

      Result

      Result Proceed to
      All stop lights illuminate when the brake pedal is depressed and turn off when the brake pedal is released. A
      All stop lights do not illuminate when the brake pedal is depressed. B
      One or more stop lights illuminate when the brake pedal is depressed but remain on when the brake pedal is released. C

    Result: 

    B 

    See step  23

    Result: 

    C 

    See step  19

    Result: 

    A 

    See step  15

  15. READ VALUE USING GTS (STOP LIGHT SWITCH ASSEMBLY) 
    1. Check the value of Stop Light SW when the brake pedal is depressed.

      Chassis > Brake/EPB > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Stop Light SW Stop light switch assembly status
      (STP or STP2 terminal input)      		 OFF / ON OFF: Brake pedal released
      ON: Brake pedal depressed      		 HINT: 
      • Stop light control relay off: STP terminal status displayed.
      • Stop light control relay on: STP2 terminal status displayed.

      Chassis > Brake/EPB > Data List 

      Tester Display
      Stop Light SW

      Result

      Result Proceed to
      The value of Stop Light SW is ON A
      None of the above conditions are met B

    Result: 

    B 

    See step  22

    Result: 

    A 

    See step  16

  16. STOP LIGHT SWITCH ASSEMBLY OUTPUT CIRCUIT INSPECTION 

    Pre-procedure1

    • Turn the ignition switch off.
    • 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-procedure2

    • Turn the ignition switch to ON.
    • Measure the voltage according to the value(s) in the table below.
      GTY1210413Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Stop Light Switch Assembly)

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      A98-1 (OUT) - Body ground
      • Ignition switch ON
      • The headlights are on
      • The blower motor switch is in the HI position
      • The rear window defogger is turned on
      • Stop light switch assembly off (Brake pedal released)
      		 Below 1.5 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    NG 

    See step  19

    Result: 

    OK 

    See step  17

  17. CLEAR DTC 

    Pre-procedure1

    • None
    • Clear the DTCs.

      Chassis > Brake/EPB > Clear DTCs 

      Result

      Proceed to
      NEXT

    Post-procedure1

    • Turn the ignition switch off.

    Result: 

    NEXT 

    See step  18

  18. RECONFIRM DTC 

    Pre-procedure1

    • Based on the Freeze Frame Data and interview with the customer, attempt to reproduce the conditions when the malfunction occurred.
    • Check if the same DTC is output.

      Chassis > Brake/EPB > Trouble Codes 

      Result

      Result Proceed to
      P0571-13 is not output A
      P0571-13 is output B

    Post-procedure1

    • None

    Result: 

    A 

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

    Result: 

    B 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [12/2023 - ] 

  19. CHECK STOP LIGHT SWITCH ASSEMBLY 

    Pre-procedure1

    • Turn the ignition switch off.
    • 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-procedure2

    • Disconnect the A98 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
      A98-1 (OUT) - Body ground Stop light switch assembly off
      (Brake pedal released)      		 Below 1.5 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    OK 

    REPLACE STOP LIGHT SWITCH ASSEMBLY. Refer to  REMOVAL [12/2023 - ] 

    Result: 

    NG 

    See step  20

  20. 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.

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      A98-1 (OUT) - Body ground Stop light switch assembly off
      (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 [12/2023 - ] 

    Result: 

    NG 

    See step  21

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

      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 

  22. CHECK HARNESS AND CONNECTOR (STP TERMINAL) 

    Pre-procedure1

    • Turn the ignition switch off.
    • 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-procedure2

    • 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.

      Standard Voltage

      Tester Connection Condition Specified Condition Result
      A6-11 (STP) - Body ground Stop light switch assembly on
      (Brake pedal depressed)      		 11 to 14 V V

      Result

      Proceed to
      OK
      NG

    Post-procedure1

    • None

    Result: 

    OK 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [12/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  23. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - STOP LIGHT) 
    1. Check that there is no open in the wire harnesses and connectors from terminal OUT of the stop light switch assembly to the stop lights.

      OK

      No open.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [12/2023 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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