CRUISE CONTROL SYSTEM, Diagnostic DTC:P0571

DTC Code DTC Name
P0571 Brake Switch "A" Circuit

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

  • Stop light switch assembly

  • Stop light switch circuit

  • Power management control ECU

WIRING DIAGRAM

A01V1A5E01
A01UZEJE01

CAUTION / NOTICE / HINT

Note

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

PROCEDURE


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


    1. for LED Type Stop Light


      1. Disconnect the stop light switch assembly connector.

      2. A01V23ZE01
        Text in Illustration
        *a

        Front view of wire harness connector

        (to Stop Light Switch Assembly)

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

        Standard Voltage
        Tester Connection Switch Condition Specified Condition
        A49-1 (B) - A49-3 (GND) Always 11 to 14 V
        A49-5 (B) - A49-3 (GND) Ignition switch ON (IG) 11 to 14 V

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

        Standard Resistance
        Tester Connection Condition Specified Condition
        A49-3 (GND) - Body ground Always Below 1 Ω

    2. for Bulb Type Stop Light


      1. Disconnect the stop light switch assembly connector.

      2. A01V26ZE02
        Text in Illustration
        *a

        Front view of wire harness connector

        (to Stop Light Switch Assembly)

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

        Standard Voltage
        Tester Connection Switch Condition Specified Condition
        A23-2 (B) - Body ground Always 11 to 14 V
        A23-4 (B) - Body ground Ignition switch ON (IG) 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. for LED Type Stop Light


      1. Reconnect the stop light switch assembly connector.

      2. A01UYQQE01
        Text in Illustration
        *a

        Component with harness connected

        (Stop Light Switch Assembly)

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

        Standard Voltage
        Tester Connection Switch Condition Specified Condition
        A49-2 (L) - A49-3 (GND) Ignition switch off, Brake pedal not depressed Below 1 V
        A49-2 (L) - A49-3 (GND) Ignition switch off, Brake pedal depressed 11 to 14 V
        A49-4 (L) - A49-3 (GND) Ignition switch ON (IG), Brake pedal not depressed 11 to 14 V
        A49-4 (L) - A49-3 (GND) Ignition switch ON (IG), Brake pedal depressed Below 1 V

    2. for Bulb Type Stop Light


      1. Remove the stop light switch assembly Click here.

      2. A01UYGDE01
        Text in Illustration
        *a

        Component with harness connected

        (Stop Light Switch Assembly)
        *b Not pushed
        *c Pushed

        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 0.1 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 200 Ω

    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    OK

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


    1. for LED Type Stop Light


      1. Disconnect the A49 stop light switch assembly connector.

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

        Standard Resistance
        Tester Connection Condition Specified Condition
        A27-23 (STP) - A49-2 (L) Always Below 1 Ω
        A27-7 (ST1-) - A49-4 (L) Always Below 1 Ω
        A27-23 (STP) or A49-2 (L) - Body ground Always 10 kΩ or higher
        A27-7 (ST1-) or A49-4 (L) - Body ground Always 10 kΩ or higher

    2. for Bulb Type Stop Light


      1. Disconnect the A23 stop light switch assembly connector.

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

        Standard Resistance
        Tester Connection Condition Specified Condition
        A27-23 (STP) - A23-1 (L) Always Below 1 Ω
        A27-7 (ST1-) - A23-3 (L) Always Below 1 Ω
        A27-23 (STP) or A23-1 (L) - Body ground Always 10 kΩ or higher
        A27-7 (ST1-) or A23-3 (L) - Body ground Always 10 kΩ or higher

    OK

    REPLACE POWER MANAGEMENT CONTROL ECU Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR