Dtc P0571 Stop Light Switch Circuit Malfunction

Engine Hybrid System. Yaris. Ncp93, 131
Cruise Control. Yaris. Ncp93, 131

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BATTERY)

INSPECT STOP LIGHT SWITCH ASSEMBLY

CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - ECM)

DTC P0571 Stop Light Switch Circuit Malfunction


DESCRIPTION

When the brake pedal is depressed, the stop light switch sends a signal to the ECM. Upon receiving the signal, the ECM cancels cruise control. Even if there is a malfunction in the stop light signal circuit while cruise control is in operation, normal driving is maintained due to a fail-safe function.
When the brake pedal is depressed, positive voltage is applied to terminal STP of the ECM through the STOP fuse and stop light switch, and the ECM cancels cruise control.

DTC Code
DTC Detection Condition
Trouble Area
P0571
The voltages of terminals ST1- and STP of the ECM are both below 1 V for 0.5 seconds or more.
  1. Stop light switch circuit
  2. Stop light switch assembly
  3. ECM

WIRING DIAGRAM


Yaris. Ncp93, 131.Cruise Control.Cruise Control System (For Sedan). Dtc P0571 Stop Light Switch Circuit Malfunction


INSPECTION PROCEDURE

NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.
1.CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BATTERY)


    Yaris. Ncp93, 131.Cruise Control.Cruise Control System (For Sedan). Dtc P0571 Stop Light Switch Circuit Malfunction

  1. Disconnect the A65 switch connector.

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

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    A65-2 - Body ground
    		Always
    		11 to 14 V
    A65-4 - Body ground
    		Ignition switch ON
    		11 to 14 V
    Ignition switch off
    		Below 1 V
    Text in Illustration
    *a
    		Front view of wire harness connector
    (to Stop Light Switch Assembly)


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


2.INSPECT STOP LIGHT SWITCH ASSEMBLY

  1. Inspect the stop light switch assembly (YARIS_NCP93 RM000001Y5401QX.html).



NG
REPLACE STOP LIGHT SWITCH ASSEMBLY (YARIS_NCP93 RM000004O2H008X.html)
OK


3.CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - ECM)

  1. Disconnect the A65 switch connector.

  1. Disconnect the A72 ECM connector.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    A65-3 - A72-10 (ST1-)
    		Always
    		Below 1 Ω
    A65-1 - A72-9 (STP)
    A65-3 - Body ground
    		Always
    		10 kΩ or higher
    A65-1 - Body ground


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE ECM (YARIS_NCP93 RM000001CN002IX.html)