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

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

  • Stop light switch assembly

  • Stop light switch assembly circuit

  • Hybrid vehicle control ECU

WIRING DIAGRAM

A005DUYE04

CAUTION / NOTICE / HINT

Note

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

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (POWER SOURCE, BODY GROUND)


    1. A005CCRE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the 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
      A80-3 (GND) - Body ground Always Below 1 Ω

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A80-1 (B) - A80-3 (GND) Always 11 to 14 V
      A80-5 (B) - A80-3 (GND) Power switch on (IG) 11 to 14 V

    4. Reconnect the stop light switch assembly connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. INSPECT STOP LIGHT SWITCH ASSEMBLY

    Inspect the stop light switch assembly Click here.


    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY

    OK

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


    1. Disconnect the hybrid vehicle control ECU 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
      A21-15 (STP) - A80-2 (OUT) Always Below 1 Ω
      A22-28 (ST1-) - A80-4 (L) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A21-15 (STP) or A80-2 (OUT) - Body ground Always 10 kΩ or higher
      A22-28 (ST1-) or A80-4 (L) - Body ground Always 10 kΩ or higher
      Result
      Result
      NG
      OK

    4. Reconnect the stop light switch assembly connector.

    5. Reconnect the hybrid vehicle control ECU connector.


    A

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    B

    REPLACE HYBRID VEHICLE CONTROL ECU Click here