DTC    P0571    Brake Switch "A" Circuit

for Preparation Click here


DESCRIPTION

When the brake pedal is depressed, the stop light switch assembly sends a signal to the power management control ECU. When the power management control ECU receives this signal, it cancels the cruise control. The fail-safe function operates to enable normal driving even if there is a malfunction in the stop light signal circuit. Cruise control cancellation occurs when voltage is applied to terminal STP. When the brake is applied, voltage is normally applied to terminal STP of the power management control ECU through the STOP fuse and the stop light switch assembly, and the power management control ECU turns the cruise control off.

DTC No.
DTC Detection Condition
Trouble Area
P0571
Voltage of STP signal and that of ST1- signal of power management control ECU are less than 1 V for 0.5 seconds or more
  1. Stop light switch assembly
  2. Stop light switch assembly circuit
  3. Power management control ECU

WIRING DIAGRAM


A217967E05


INSPECTION PROCEDURE

NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.

1.INSPECT STOP LIGHT SWITCH ASSEMBLY (POWER SOURCE)


    A194115E71

  1. Disconnect the stop light switch assembly connector.

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

    Standard Voltage:
    Tester Connection
    		Condition
    		Specified Condition
    A25-2 - Body ground
    		Always
    		11 to 14 V

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

  1. Reconnect the stop light switch assembly connector.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BATTERY)
OK


2.INSPECT STOP LIGHT SWITCH ASSEMBLY (POWER SOURCE)


    A194115E71

  1. Disconnect the stop light switch assembly connector.

  1. Turn the power switch on (IG).

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

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    A25-4 - Body ground
    		Power switch on (IG)
    		11 to 14 V

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

  1. Reconnect the stop light switch assembly connector.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - IG2 RELAY)
OK


3.INSPECT STOP LIGHT SWITCH ASSEMBLY


    A167698E20

  1. Remove the stop light switch assembly (Click here).

  1. 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

    Text in Illustration 
    *a
    		Component without harness connected
    (Stop Light Switch Assembly)
    *b
    		Not pushed
    *c
    		Pushed

  1. Reinstall the stop light switch assembly (Click here).



NG
REPLACE STOP LIGHT SWITCH ASSEMBLY (Click here)
OK


4.CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU - STOP LIGHT SWITCH ASSEMBLY)

  1. Disconnect the power management control ECU connector.

  1. Disconnect the stop light switch assembly connector.

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

    Standard Resistance (Check for Open):
    Tester Connection
    		Condition
    		Specified Condition
    A20-23 (STP) - A25-1
    		Always
    		Below 1 Ω
    A20-7 (ST1-) - A25-3
    		Always
    		Below 1 Ω

    Standard Resistance (Check for Short):
    Tester Connection
    		Condition
    		Specified Condition
    A20-23 (STP) or A25-1 - Body ground
    		Always
    		10 kΩ or higher
    A20-7 (ST1-) or A25-3 - Body ground
    		Always
    		10 kΩ or higher

  1. Reconnect the stop light switch assembly connector.

  1. Reconnect the power management control ECU connector.



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER MANAGEMENT CONTROL ECU - STOP LIGHT SWITCH ASSEMBLY)
OK

REPLACE POWER MANAGEMENT CONTROL ECU (Click here)