DTC P0571: Stop Light Switch Circuit Malfunction [01/2019 - 09/2022]: Procedure

1. Check if electronically controlled brake system DTCs are output.

   Chassis > Brake > Trouble Codes 

   Result

   Result	Proceed to
   Electronically controlled brake system DTCs are not output	A
   Electronically controlled brake system DTCs are output	B

Result: 

B 

GO TO ELECTRONICALLY CONTROLLED BRAKE SYSTEM 

w/ Electric Parking Brake System: Refer to HOW TO PROCEED WITH TROUBLESHOOTING [06/2018 - 09/2022]

w/o Electric Parking Brake System: Refer to HOW TO PROCEED WITH TROUBLESHOOTING [01/2019 - 09/2022]

Result: 

A 

See step  2

1. Disconnect the A53 stop light switch assembly connector.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Front view of wire harness connector (to Stop Light Switch Assembly)

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A53-2 (GND) - Body ground	Always	Below 1 Ω

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

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   A53-7 (B) - Body ground	Always	11 to 14 V
   A53-6 (B) - Body ground	Ignition switch ON	11 to 14 V
   A53-6 (B) - Body ground	Ignition switch off	Below 1 V

4. Connect the A53 stop light switch assembly connector.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  3

1. Inspect the stop light switch assembly.

   Refer to ON-VEHICLE INSPECTION [01/2019 - ]

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPLACE STOP LIGHT SWITCH ASSEMBLY. Refer to  COMPONENTS [06/2018 - ] 

Result: 

OK 

See step  4

1. Disconnect the A46 ECM connector.
2. Disconnect the A53 stop light switch assembly connector.
3. Disconnect the A51 skid control ECU (brake actuator assembly) connector.*4
4. Disconnect the A100 skid control ECU (brake actuator assembly) connector.*5
5. Disconnect the O61 certification ECU (smart key ECU assembly) connector.*1
6. Disconnect the I17 shift lock control ECU (shift lock control unit assembly) connector.*2
7. Disconnect the I18 shift lock control ECU (shift lock control unit assembly) connector.*3
8. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A53-5 (L) - A46-10 (ST1-)	Always	Below 1 Ω
   A53-3 (L) - A46-9 (STP)	Always	Below 1 Ω
   A53-5 (L) or A46-10 (ST1-) - Body ground	Always	10 kΩ or higher
   A53-3 (L) or A46-9 (STP) - Body ground	Always	10 kΩ or higher

9. Connect the I18 shift lock control ECU (shift lock control unit assembly) connector.*3
10. Connect the I17 shift lock control ECU (shift lock control unit assembly) connector.*2
11. Connect the O61 certification ECU (smart key ECU assembly) connector.*1
12. Connect the A100 skid control ECU (brake actuator assembly) connector.*5
13. Connect the A51 skid control ECU (brake actuator assembly) connector.*4
14. Connect the A53 stop light switch assembly connector.
15. Connect the A46 ECM connector.
    1. *1: w/ Smart Key System
    2. *2: for CVT without Smart Key System
    3. *3: for CVT with Smart Key System
    4. *4: w/ Electrical Parking Brake System
    5. *5: w/o Electrical Parking Brake System

    Result

    Proceed to
    OK
    NG

Result: 

OK 

REPLACE ECM. Refer to  COMPONENTS [01/2019 - 11/2022] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR