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 hybrid vehicle control ECU assembly. When the hybrid vehicle control ECU assembly receives this signal, it cancels control of vehicle speed by the cruise control system. The 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 assembly through the STOP fuse and the stop light switch assembly, and the hybrid vehicle control ECU assembly turns the cruise control system off.

DTC No. Detection Item DTC Detection Condition Trouble Area
P0571 Brake Switch "A" Circuit Voltage of STP signal and that of ST1- terminal of hybrid vehicle control ECU assembly are less than 1 V for 0.5 seconds or more

  • Stop light switch assembly

  • Stop light switch assembly circuit

  • Hybrid vehicle control ECU assembly

WIRING DIAGRAM

A01KTWZE03

CAUTION / NOTICE / HINT

Note

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

PROCEDURE


  1. INSPECT STOP LIGHT SWITCH ASSEMBLY (POWER SOURCE)


    1. A01KSFUC26
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the stop light switch assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A1-2 - Body ground Power switch off 11 to 14 V

    3. Reconnect the stop light switch assembly connector.

      Result
      Proceed to
      OK
      NG

    NG

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

    OK

  2. INSPECT STOP LIGHT SWITCH ASSEMBLY (POWER SOURCE)


    1. A01KSFUC26
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the stop light switch assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A1-4 - Body ground Power switch on (IG) 11 to 14 V

    3. Reconnect the stop light switch assembly connector.

      Result
      Proceed to
      OK
      NG

    NG

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

    OK

  3. INSPECT STOP LIGHT SWITCH ASSEMBLY (POWER SOURCE)


    1. Inspect the stop light switch assembly.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    OK

  4. CHECK HARNESS AND CONNECTOR (HYBRID VEHICLE CONTROL ECU ASSEMBLY - STOP LIGHT SWITCH ASSEMBLY)


    1. Disconnect the hybrid vehicle control ECU assembly connector.

    2. Disconnect the stop light switch assembly connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A149-15 (STP) - A124-1 Always Below 1 Ω
      A150-28 (ST1-) - A124-3 Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A149-15 (STP) or A124-1 - Body ground Always 10 kΩ or higher
      A150-28 (ST1-) or A124-3 - Body ground Always 10 kΩ or higher

    4. Reconnect the stop light switch assembly connector.

    5. Reconnect the hybrid vehicle control ECU assembly connector.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY for LHD: Click here
    REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY for RHD: Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR