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 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

A017BGSE02
A017EDAE02

INSPECTION PROCEDURE

PROCEDURE


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


    1. A017EVIE03

      Disconnect the A20 connector from the stop light switch.

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

      Standard voltage
      Tester Connection Condition Specified Condition
      A20-2 - Body ground Always 11 to 14 V
      A20-3 - Body ground Ignition switch on (IG) 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. INSPECT STOP LIGHT SWITCH


    1. Remove the stop light switch Click here.

    2. A017E86E01

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

      Standard resistance
      Tester Connection Switch Condition Specified Condition
      1 - 2 Switch pin not pushed Below 1 Ω
      3 - 4 Switch pin not pushed 10 kΩ or higher
      1 - 2 Switch pin pushed 10 kΩ or higher
      3 - 4 Switch pin pushed Below 1 Ω

    3. Install the stop light switch Click here.


    NG

    REPLACE STOP LIGHT SWITCH

    OK

  3. CHECK ECM


    1. A017FGWE02

      Disconnect the D31 connector from the ECM.

    2. Turn the ignition switch on (IG).

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

      Standard voltage
      Tester Connection Condition Specified Condition
      D31-15 (STP) - Body ground Brake pedal is depressed 11 to 14 V
      D31-15 (STP) - Body ground Brake pedal is released Below 1 V
      D31-16 (ST1-) - Body ground Brake pedal is depressed Below 1 V
      D31-16 (ST1-) - Body ground Brake pedal is released 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH - ECM)

    OK

    REPLACE ECM (for 2GR-FE) Click here