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 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 switch assembly signal circuit. The cancellation condition occurs when voltage is applied to terminal STP. When the brake pedal is depressed, voltage is 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 cancels control of vehicle speed by the cruise control system.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

P0571

Brake Switch "A" Circuit

The voltage of the STP and ST1- terminals of the hybrid vehicle control ECU are less than 1 V for 0.5 seconds or more.

  • Stop light switch assembly

  • Hybrid vehicle control ECU

  • Harness or connector

WIRING DIAGRAM

E341864E04
E341864E05

CAUTION / NOTICE / HINT

Note:

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

PROCEDURE

  1. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BATTERY)

    1. Disconnect the stop light switch assembly connector.

    2. E270270C21

      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly) (for RHD)
      E239037C50

      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly) (for LHD)

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

      Standard Voltage (for LHD)

      Tester Connection

      Condition

      Specified Condition

      A100-1 (B) - Body ground

      Always

      11 to 14 V

      A100-5 (B) - Body ground

      Power switch on (IG)

      11 to 14 V

      A100-5 (B) - Body ground

      Power switch off

      Below 1 V

      Standard Voltage (for RHD)

      Tester Connection

      Condition

      Specified Condition

      A77-7 (B) - Body ground

      Always

      11 to 14 V

      A77-6 (B) - Body ground

      Power switch on (IG)

      11 to 14 V

      A77-6 (B) - Body ground

      Power switch off

      Below 1 V

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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

    1. C351003C02

      *a

      Front view of wire harness connector

      (to Hybrid Vehicle Control ECU)

      Disconnect the hybrid vehicle control ECU connector.

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      A66-28 (ST1-) - Body ground

      Power switch on (IG), brake pedal depressed

      0 to 1.5 V

      Power switch on (IG), brake pedal released

      11 to 14 V

      A65-15 (STP) - Body ground

      Brake pedal depressed

      11 to 14 V

      Brake pedal released

      0 to 1.5 V

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK STOP LIGHT SWITCH ASSEMBLY

    1. Temporarily replace the stop light switch assembly with a new or normally functioning one.

      Click here

    2. Clear the DTCs.

      Click here

      Powertrain > Cruise Control > Clear DTCs

    3. Make sure that the DTC detection conditions are met.

      Tip:

      If the detection conditions are not met, the system cannot detect the malfunction.

    4. Check for DTCs.

      Click here

      Powertrain > Cruise Control > Trouble Codes

    Result

    Result

    Proceed to

    DTC is not output

    A

    DTC P0571 is output

    B
    A

    END (STOP LIGHT SWITCH ASSEMBLY WAS DEFECTIVE)

    B

    REPLACE HYBRID VEHICLE CONTROL ECU

    Click here