DTC    P0571    Brake Switch "A" Circuit

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DESCRIPTION

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

DTC No.
DTC Detection Condition
Trouble Area
P0571
When voltage of STP terminal and that of ST1- terminal on the hybrid vehicle control ECU are less than 1 V for 0.5 sec. or more
  1. Stop light switch
  2. Stop light switch circuit
  3. Hybrid vehicle control ECU

WIRING DIAGRAM


E109946E01


INSPECTION PROCEDURE

1.READ VALUE OF INTELLIGENT TESTER

  1. Connect the intelligent tester to the DLC3.

  1. Turn the ignition switch on, and turn the intelligent tester main switch on.

  1. Check the DATA LIST for proper functioning of the stop light switch.

    Hybrid Vehicle Control ECU (Cruise control): 
    Item
    		Measurement Item / Display (Range)
    		Normal Condition
    		Diagnostic Note
    STP LIGHT SW M
    		Stop light switch signal (Main CPU) / ON or OFF
    		ON: Brake pedal depressed
    OFF: Brake pedal released
    		-

    OK:
    When brake pedal operation is performed the results will be same as above.



OK
REPLACE HYBRID VEHICLE CONTROL ECU
NG


2.INSPECT STOP LIGHT SWITCH

  1. Disconnect the stop light switch connector.



    E067360E02

  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



NG
REPLACE STOP LIGHT SWITCH
OK


3.CHECK WIRE HARNESS (STOP LIGHT SWITCH - BATTERY)


    I039310E01

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

    Standard voltage:
    Tester Connection
    		Condition
    		Specified Condition
    S13-2 - Body ground
    		Always
    		10 to 14 V
    S13-3 - Body ground
    		Engine switch on (IG)
    		10 to 14 V



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


4.CHECK HYBRID VEHICLE CONTROL ECU

  1. Reconnect the stop light switch connector.

  1. Disconnect the H29 connector from the hybrid vehicle control ECU.

  1. Turn the ignition switch on.



    E110177E10

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

    Standard voltage:
    Tester Connection
    		Brake Pedal Condition
    		Condition
    H29-31 (STP) - Body ground
    		Depressed
    		10 to 14 V
    H29-31 (STP) - Body ground
    		Released
    		Below 1 V
    H29-25 (ST1-) - Body ground
    		Depressed
    		Below 1 V
    H29-25 (ST1-) - Body ground
    		Released
    		10 to 14 V



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH - HYBRID VEHICLE CONTROL ECU)
OK

REPLACE HYBRID VEHICLE CONTROL ECU