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 ECM. When the ECM 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 ECM through the STOP fuse and the stop light switch assembly, and the ECM cancels control of vehicle speed by the cruise control system.

DTC No. Detection Item DTC Detection Condition Trouble Area
P0571 Brake Switch "A" Circuit When the ignition switch is ON and the cruise control system is operating, the voltage of the STP and ST1- terminals of the ECM are less than 1 V for 0.5 seconds or more.

  • Stop light switch assembly

  • Harness or connector

  • ECM

WIRING DIAGRAM

A002AMKE02

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 AND BODY GROUND)


    1. A00285TC03
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the A87 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
      A87-2 (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
      A87-7 (B) - Body ground Always 11 to 14 V
      A87-6 (B) - Body ground Ignition switch ON 11 to 14 V
      A87-6 (B) - Body ground Ignition switch off Below 1 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. Inspect the stop light switch assembly.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    OK

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


    1. Disconnect the A43 ECM connector.

    2. Disconnect the A87 stop light switch assembly connector.

    3. Disconnect the A86 skid control ECU (brake actuator assembly) connector.

    4. Disconnect the F10 certification ECU (smart key ECU assembly) connector (w/ Smart Entry and Start System).

    5. Disconnect the F48 transmission floor shift assembly (shift lock control unit) connector (w/ Smart Entry and Start System).

    6. Disconnect the F47 transmission floor shift assembly (shift lock control unit) connector (w/o Smart Entry and Start System).

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A43-24 (ST1-) - A87-5 (L) Always Below 1 Ω
      A43-11 (STP) - A87-3 (L) Always Below 1 Ω
      A43-24 (ST1-) or A87-5 (L) - Body ground Always 10 kΩ or higher
      A43-11 (STP) or A87-3 (L) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR