DTC P0571-62: Brake Switch "A" Signal Compare Failure [11/2023 - ]: Procedure

1. Read the Data List according to the display on the GTS.

   Body Electrical > Power Source Control > Data List 

   Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
   Stop Light Switch	State of brake pedal	OFF or ON	OFF: Brake pedal released	Use this item to determine if the stop light switch assembly is malfunctioning. The engine cannot be started when this item is OFF. If the stop light switch assembly is malfunctioning, the engine can be started by pressing and holding the engine switch for a certain period of time.

   Body Electrical > Power Source Control > Data List 

   Tester Display
   Stop Light Switch

   OK

   The GTS display changes correctly in response to the brake pedal operation.

   Result

   Result	Proceed to
   The value of Stop Light Switch is OFF	A
   The value of Stop Light Switch is not OFF	B

Result: 

B 

See step  3

Result: 

A 

See step  2

1. Read the Data List according to the display on the GTS.

   Body Electrical > Power Source Control > Data List 

   Tester Display	Measurement Item	Range	Normal Condition	Diagnostic Note
   Stop Light Switch	State of brake pedal	OFF or ON	ON: Brake pedal depressed	Use this item to determine if the stop light switch assembly is malfunctioning. The engine cannot be started when this item is OFF. If the stop light switch assembly is malfunctioning, the engine can be started by pressing and holding the engine switch for a certain period of time.

   Body Electrical > Power Source Control > Data List 

   Tester Display
   Stop Light Switch

   OK

   The GTS display changes correctly in response to the brake pedal operation.

   Result

   Result	Proceed to
   The value of Stop Light Switch is ON	A
   The value of Stop Light Switch is not ON	B

Result: 

A 

GO TO ELECTRONICALLY CONTROLLED BRAKE SYSTEM (HOW TO PROCEED WITH TROUBLESHOOTING). Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2023 - ] 

Result: 

B 

See step  3

Pre-procedure1

1. Disconnect the A88 certification ECU (smart key ECU assembly) connector.
2. Disconnect the A42 stop light switch assembly connector.
3. Disconnect the A39 skid control ECU (brake actuator assembly) connector.
4. Disconnect the A83 ECM connector.

   Procedure1

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A88-21 (STP1) - A42-3 (L)	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

   Post-procedure1

6. None

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  4

Pre-procedure1

1. Connect the A88 certification ECU (smart key ECU assembly) connector.
2. Connect the A42 stop light switch assembly connector.

   Procedure1

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

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Component with harness connected (Certification ECU (Smart Key ECU Assembly))

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A88-21 (STP1) - Body ground	Brake pedal released	1 V or less
   A88-21 (STP1) - Body ground	Brake pedal depressed	9 V or higher

   Result

   Proceed to
   OK
   NG

   Post-procedure1

4. None

Result: 

OK 

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [11/2023 - ] 

Result: 

NG 

REPLACE STOP LIGHT SWITCH ASSEMBLY. Refer to  REMOVAL [12/2019 - ]