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DTC P0571: Brake Switch "A" Circuit [08/2013 - ]: Procedure

WARNING: This page is about a different car, the 2014 Lexus ES 300h. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT) 
    1. Disconnect the A28 stop light switch assembly connector.
      GTY416071Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Condition Specified Condition
      A28-1 (B) - A28-3 (GND) Power switch off 11 to 14 V
      A28-5 (B) - A28-3 (GND) Power switch on (IG) 11 to 14 V
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A28-3 (GND) - Body ground Always Below 1 Ω
      TEXT IN ILLUSTRATION

      *a Front view of wire harness connector
      (to Stop Light Switch Assembly)
    4. Reconnect the A28 stop light switch assembly connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  2. INSPECT STOP LIGHT SWITCH ASSEMBLY 
    1. Measure the voltage according to the value(s) in the table below.
      GTY401064Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard Voltage

      Tester Connection Condition Specified Condition
      A28-2 (L) - A28-3 (GND) Power switch off, brake pedal not depressed Below 1 V
      Power switch off, brake pedal depressed 11 to 14 V
      A28-4 (L) - A28-3 (GND) Power switch on (IG), brake pedal not depressed 11 to 14 V
      Power switch on (IG), brake pedal depressed Below 1 V
      TEXT IN ILLUSTRATION

      *a Component with harness connected
      (Stop Light Switch Assembly)

    NG → See step   5 

    OK: Go to next step 

  3. CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU - STOP LIGHT SWITCH ASSEMBLY) 
    1. Disconnect the A33 power management control ECU connector.
    2. Disconnect the A28 stop light switch assembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)

      Tester Connection Condition Specified Condition
      A33-23 (STP) - A28-2 (L) Always Below 1 Ω
      A33-7 (ST1-) - A28-4 (L) Always Below 1 Ω

      Standard Resistance (Check for Short)

      Tester Connection Condition Specified Condition
      A33-23 (STP) or A28-2 (L) - Body ground Always 10 kΩ or higher
      A33-7 (ST1-) or A28-4 (L) - Body ground Always 10 kΩ or higher
    4. Reconnect the A28 stop light switch assembly connector.
    5. Reconnect the A33 power management control ECU connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK → See step   4 

  4. REPLACE POWER MANAGEMENT CONTROL ECU. Refer to  REMOVAL [08/2013 - ] 
  5. REPLACE STOP LIGHT SWITCH ASSEMBLY. Refer to  REMOVAL [08/2013 - ] 
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