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 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 assembly through the STOP fuse and the stop light switch assembly, and the hybrid vehicle control ECU assembly 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 assembly are less than 1 V for 0.5 seconds or more.

  • Stop light switch assembly

  • Harness or connector

  • Hybrid vehicle control ECU assembly

WIRING DIAGRAM

A01OADSE01

CAUTION / NOTICE / HINT

Note

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

Tech Tips

After performing repairs on the vehicle, clear the DTCs and perform the following procedure to check that DTCs are not output.


  1. Turn the power switch on (IG).

  2. Turn the cruise control system on using the cruise control switch (ON/OFF button).

  3. Depress the brake pedal for 0.5 seconds or more.

PROCEDURE


  1. CHECK TERMINAL VOLTAGE (POWER SOURCE OF STOP LIGHT SWITCH ASSEMBLY)


    1. B004FUQC46
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the A52 stop light switch assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A52-1 (B) - A52-3 (GND) Power switch off 11 to 14 V
      A52-5 (B) - A52-3 (GND) Power switch on (IG) 11 to 14 V
      Standard Resistance
      Tester Connection Condition Specified Condition
      A52-3 (GND) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - AUXILIARY BATTERY AND BODY GROUND)

    OK

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


    1. Disconnect the A81 and A80 hybrid vehicle control ECU assembly connectors.

    2. Disconnect the A52 stop light switch assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A81-28 (ST1-) - A52-4 (L) Always Below 1 Ω
      A80-15 (STP) - A52-2 (L) Always Below 1 Ω
      A81-28 (ST1-) or A52-4 (L) - Body ground Always 10 kΩ or higher
      A80-15 (STP) or A52-2 (L) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. REPLACE STOP LIGHT SWITCH ASSEMBLY


    1. Replace the stop light switch assembly.

      Click here

      Result
      Proceed to
      NEXT

    NEXT

  4. CHECK FOR DTCs (CRUISE CONTROL SYSTEM)


    1. Clear the DTCs.

      Click here


      Powertrain > Cruise Control > Clear DTCs

    2. Perform the following to make sure that the DTC detection conditions are met.

      Tech Tips

      If the detection conditions are not met, the malfunction cannot be detected.


      1. Turn the cruise control system on using the cruise control switch (ON/OFF button).

    3. Check for DTCs.

      Click here


      Powertrain > Cruise Control > Trouble Codes
      Result
      Result Proceed to
      DTC P0571 is not output A
      DTC P0571 is output B

    A

    END (STOP LIGHT SWITCH ASSEMBLY WAS DEFECTIVE)

    B

    REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY Click here