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Home >> Lexus >> 2022 >> LS 500h AWD >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> Electronically Controlled Brake System (W/ Advanced Park) - Diagnostic Codes (5 Of 5) & Symptom Tests >> ELECTRONICALLY CONTROLLED BRAKE SYSTEM (w/ Advanced Park) >> DTC P0571-13: Brake Switch "A" Circuit Open [11/2021 - 10/2023] >> Procedure

DTC P0571-13: Brake Switch "A" Circuit Open [11/2021 - 10/2023]: Procedure

  1. 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  11

    Result: 

    C 

    See step  6

    Result: 

    A 

    See step  2

  2. 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
      Other than above. B

    Result: 

    B 

    See step  8

    Result: 

    A 

    See step  3

  3. STOP LIGHT SWITCH ASSEMBLY OUTPUT CIRCUIT INSPECTION 
    1. Turn the ignition switch off.
      GTY979635Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (Stop Light Switch Assembly)
    2. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK

      The connector is securely connected.

    3. Turn the ignition switch to ON.
    4. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      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

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  6

    Result: 

    OK 

    See step  4

  4. CLEAR DTC 
    1. Clear the DTCs.

      Chassis > Brake/EPB > Clear DTCs 

    2. Turn the ignition switch off.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  5

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

      Chassis > Brake/EPB > Trouble Codes 

      Result

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

    Result: 

    A 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2021 - 10/2022]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2022 - 10/2023] 

    Result: 

    B 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

  6. CHECK STOP LIGHT SWITCH ASSEMBLY 
    1. Turn the ignition switch off.
    2. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK

      The connector is securely connected.

    3. Disconnect the A3 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
      A3-2 (L) - Body ground Stop light switch assembly off
      (Brake pedal released)      		 Below 1.5 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE STOP LIGHT SWITCH ASSEMBLY. Refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

    Result: 

    NG 

    See step  7

  7. CHECK 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.

    2. Disconnect the A102 No. 2 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
      A3-2 (L) - Body ground Stop light switch assembly off
      (Brake pedal released)      		 Below 1.5 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

    Result: 

    NG 

    See step  9

  8. CHECK HARNESS AND CONNECTOR (STP TERMINAL) 
    1. Turn the ignition switch off.
    2. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK

      The connector is securely connected.

    3. Disconnect the A102 No. 2 skid control ECU (brake actuator 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
      A3-2 (L) - Body ground Stop light switch assembly on
      (Brake pedal depressed)      		 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  9. CHECK NO. 3 SEMICONDUCTOR POWER INTEGRATION ECU 
    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.

    2. Disconnect the L111 No. 3 semiconductor power integration ECU 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
      A3-2 (L) - Body ground Stop light switch assembly off
      (Brake pedal released)      		 Below 1.5 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE NO. 3 SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

    Result: 

    NG 

    See step  10

  10. 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 [11/2021 - 10/2022]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2022 - 10/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE MALFUNCTIONING PART 

  11. CHECK NO. 3 SEMICONDUCTOR POWER INTEGRATION ECU 
    1. Make sure that there is no looseness at the locking part and the connecting part of the connectors.
      GTY1086403Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      *a Component with harness connected
      (No. 3 Semiconductor Power Integration ECU)

      OK

      The connector is securely connected.

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

      Standard Voltage

      Tester Connection Condition Specified Condition
      L111-10 (STP) - Body ground Stop light switch assembly on
      (Brake pedal depressed)      		 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE NO. 3 SEMICONDUCTOR POWER INTEGRATION ECU. Refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

    Result: 

    NG 

    See step  12

  12. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - NO. 3 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. 3 semiconductor power integration ECU.

      OK

      No open.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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