DTC P0571: Stop Light Switch Circuit Malfunction: Procedure

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Disconnect the A77 stop light switch assembly connector.
2. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Condition	Specified Condition
   A77-1 (B) - Body ground	Always	11 to 14 V
   A77-5 (B) - Body ground	Engine switch on (IG)

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

   Standard resistance

   Tester Connection	Condition	Specified Condition
   A77-3 (GND) - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Disconnect the A14 ECM connector.
2. Disconnect the A77 stop light switch assembly connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   A14-12 (ST1-) - A77-4 (L)	Always	Below 1 Ω
   A14-13 (STP) - A77-2 (L)
   A14-12 (ST1-) - Body ground	Always	10 kΩ or higher
   A14-13 (STP) - Body ground

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Temporarily replace the stop light switch assembly with a new or normally functioning one. Refer to REMOVAL [09/2012 - ] .
2. Clear the DTC. Refer to DTC CHECK / CLEAR [09/2012 - ] .
3. Recheck for the DTC. Refer to DTC CHECK / CLEAR [09/2012 - ] .

   OK

   DTC P0571 is not output.

NG → See step   4 

OK → END (STOP LIGHT SWITCH ASSEMBLY IS DEFECTIVE)