DTC P0571: Brake Switch "A" Circuit: Procedure

1. Disconnect the stop light switch connector.
   Fig 1: Identifying Terminals Of Stop Light Switch A22 Connector

   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
   A22-2 - Body ground	Always	11 to 14 V
   A22-4 - Body ground	Engine switch on (IG)	11 to 14 V

3. Reconnect the stop light switch connector.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

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

   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. Refer to INSTALLATION .

NG → See step   5 

OK: Go to next step 

1. Disconnect the ECM connector.
   Fig 3: Identifying Terminals Of A5 Connector

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A5-13 (STP) - Body ground	Brake pedal depressed	11 to 14 V
   A5-13 (STP) - Body ground	Brake pedal released	Below 1 V
   A5-12 (ST1-) - Body ground	Brake pedal depressed	Below 1 V
   A5-12 (ST1-) - Body ground	Brake pedal released	11 to 14 V

4. Reconnect the ECM connector.

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

OK → See step   4