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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
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


E235740E08


INSPECTION PROCEDURE

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

1.CHECK WIRE HARNESS AND CONNECTOR (STOP LIGHT SWITCH POWER SOURCE)

  1. Disconnect the stop light switch assembly connector.



    E233265E10

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

    Standard Voltage:
    Tester Connection
    		Condition
    		Specified Condition
    A67-1 (B) - A67-3 (GND)
    		Power switch off
    		11 to 14 V
    A67-5 (B) - A67-3 (GND)
    		Power switch on (IG)
    		11 to 14 V

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    A67-3 (GND) - ground
    		Always
    		Below 1 Ω

    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 (POWER SOURCE)

  1. Reconnect the stop light switch assembly connector.



    E233266E08

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

    Standard Voltage:
    Tester Connection
    		Switch Condition
    		Specified Condition
    A67-2 (L) - A67-3 (GND)
    		Power switch off , brake pedal not depressed
    		Below 1 V
    Power switch off , brake pedal depressed
    		11 to 14 V
    A67-4 (L) - A67-3 (GND)
    		Power switch off , brake pedal not depressed
    		Below 1V
    Power switch off , brake pedal depressed
    		11 to 14 V

    Text in Illustration 
    *a
    		Component with harness connected
    (to Stop Light Switch Assembly)



NG
REPLACE STOP LIGHT SWITCH ASSEMBLY (Click here)
OK


3.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
    A22-23 (STP) - A67-4 (L)
    		Always
    		Below 1 Ω
    A22-7 (ST1-) - A67-2 (L)
    		Always
    		Below 1 Ω

    Standard Resistance (Check for Short):
    Tester Connection
    		Condition
    		Specified Condition
    A22-23 (STP) or A67-4 (L) - Body ground
    		Always
    		10 kΩ or higher
    A22-7 (ST1-) or A67-2 (L) - Body ground
    		Always
    		10 kΩ or higher



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

REPLACE POWER MANAGEMENT CONTROL ECU (Click here)