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 sends a signal to the ECM. When the ECM 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. 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 ECM through the STOP SW fuse and the stop light switch, and the ECM turns the cruise control off.

DTC No. DTC Detection Condition Trouble Area
P0571 Voltage of STP terminal and that of ST1- terminal of ECM are less than 1 V for 0.5 sec. or more

  • Stop light switch

  • Stop light switch circuit

  • ECM

WIRING DIAGRAM

A019KU3E01

INSPECTION PROCEDURE

Tech Tips

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

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)


    1. A019OXLE38
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Stop Light Switch)

      Disconnect the stop light switch connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A79-1 (B) - A79-3 (GND) Engine switch off 11 to 14 V
      A79-5 (B) - A79-3 (GND) Engine switch on (IG) 11 to 14 V
      Standard Resistance
      Tester Connection Condition Specified Condition
      A79-3 (GND) - Body ground Always Below 1 Ω

    3. Reconnect the stop light switch connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. INSPECT STOP LIGHT SWITCH


    1. A019LRUE36
      Text in Illustration
      *1

      Component with harness connected

      (Stop Light Switch)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A79-2 (L) - A79-3 (GND) Engine switch off, brake pedal not depressed Below 1 V
      Engine switch off, brake pedal depressed 11 to 14 V
      A79-4 (L) - A79-3 (GND) Engine switch on (IG), brake pedal not depressed 11 to 14 V
      Engine switch on (IG), brake pedal depressed Below 1 V

    NG

    REPLACE STOP LIGHT SWITCH Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM)


    1. Disconnect the stop light switch connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance (Check for Open)
      for 2GR-FE
      Tester Connection Condition Specified Condition
      A79-2 (L) - A43-36 (STP) Always Below 1 Ω
      A79-4 (L) - A43-35 (ST1-) Always Below 1 Ω
      for 1AR-FE
      Tester Connection Condition Specified Condition
      A79-2 (L) - A70-29 (STP) Always Below 1 Ω
      A79-4 (L) - A70-39 (ST1-) Always Below 1 Ω
      Standard Resistance (Check for Short)
      for 2GR-FE
      Tester Connection Condition Specified Condition
      A79-2 (L) or A43-36 (STP) - Body ground Always 10 kΩ or higher
      A79-4 (L) or A43-35 (ST1-) - Body ground Always 10 kΩ or higher
      for 1AR-FE
      Tester Connection Condition Specified Condition
      A79-2 (L) or A70-29 (STP) - Body ground Always 10 kΩ or higher
      A79-4 (L) or A70-39 (ST1-) - Body ground Always 10 kΩ or higher
      Result
      Result Proceed to
      OK (for 2GR-FE) A
      OK (for 1AR-FE) B
      NG C

    4. Reconnect the ECM connector.

    5. Reconnect the stop light switch connector.


    B

    REPLACE ECM (for 1AR-FE) Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

    REPLACE ECM (for 2GR-FE) Click here