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 signal circuit. The cancellation condition occurs when voltage is applied to terminal STP. When the brake is applied, 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 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 assembly

  • Stop light switch circuit

  • ECM

WIRING DIAGRAM

A018K84E17

CAUTION / NOTICE / HINT

Note

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

PROCEDURE


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


    1. Disconnect the A54 stop light switch assembly connector.

    2. A018K8IC14
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A54-2 - Body ground Always 11 to 14 V
      A54-4 - Body ground Ignition switch ON 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BATTERY OR IG2 RELAY)

    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 A54 stop light switch assembly connector.

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

      Standard Resistance
      for 1AR-FE
      Tester Connection Condition Specified Condition
      A43-11 (STP) - A54-1 Always Below 1 Ω
      A43-24 (ST1-) - A54-3 Always Below 1 Ω
      A43-11 (STP) or A54-1 - Body ground Always 10 kΩ or higher
      A43-24 (ST1-) or A54-3 - Body ground Always 10 kΩ or higher
      for 2GR-FE
      Tester Connection Condition Specified Condition
      A43-36 (ST1-) - A54-3 Always Below 1 Ω
      A43-51 (STP) - A54-1 Always Below 1 Ω
      A43-36 (ST1-) or A54-3 - Body ground Always 10 kΩ or higher
      A43-51 (STP) or A54-1 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECM for 1AR-FE: Click here
    REPLACE ECM for 2GR-FE: Click here

    NG

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