DTC P0571: Brake Switch "A" Circuit: Procedure

1. Disconnect the stop light switch assembly connector.
   Fig 1: Stop Light Switch Assembly Connector End View (A1)

   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

3. Reconnect the stop light switch assembly connector.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Remove the stop light switch assembly. Refer to COMPONENTS .
   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. Disconnect the ECM connector.
   Fig 3: Identifying A50 ECM Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Turn the ignition switch to ON.
3. Measure the voltage according to the value(s) in the table below.

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A50-36 (STP) - Body ground	Brake pedal depressed	11 to 14 V
   A50-36 (STP) - Body ground	Brake pedal released	Below 1 V
   A50-35 (ST1-) - Body ground	Brake pedal depressed	Below 1 V
   A50-35 (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

4. Reconnect the ECM connector.

B → See step   5 

C → See step   6 

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