DTC P0571: Brake Switch "A" Circuit: Procedure

1. Disconnect the stop light switch assembly connector.
   Fig 1: Identifying A1 Stop Light Switch Assembly Connector Terminals

   Courtesy 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
   A1-2 - Body ground	Always	11 to 14 V
   A1-3 - Body ground	Ignition switch ON	11 to 14 V

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Remove the stop light switch assembly. Refer to REMOVAL .
   Fig 2: Inspecting Stop Light Switch Assembly

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Switch Condition	Specified Condition
   1 - 2	Switch pin not pushed	Below 1 Ω
   3 - 4	Switch pin not pushed	10 kΩ or higher
   1 - 2	Switch pin pushed	10 kΩ or higher
   3 - 4	Switch pin pushed	Below 1 Ω

3. Install the stop light switch assembly. Refer to INSTALLATION .

NG → See step   4 

OK: Go to next step 

1. Reconnect the stop light switch assembly connector.
   Fig 3: Checking A37 ECM Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the ECM connector.
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
   A37-36 (STP) - Body ground	Brake pedal depressed	11 to 14 V
   A37-36 (STP) - Body ground	Brake pedal released	Below 1 V
   A37-35 (ST1-) - Body ground	Brake pedal depressed	Below 1 V
   A37-35 (ST1-) - Body ground	Brake pedal released	11 to 14 V

   Result

   Result	Proceed to
   NG	A
   OK (for 2ZR-FE)	B
   OK (for 2AZ-FE)	C

B → See step   5 

C → See step   6 

A → REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - ECM)