CRUISE CONTROL SYSTEM, Diagnostic DTC:P0571

DTC Code DTC Name
P0571 Stop Light Switch Circuit Malfunction

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 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 Code DTC Detection Condition Trouble Area
P0571 When the voltage of the STP terminal and the ST1- terminal of the ECM is below 1 V for 0.5 sec. or more.

  • Stop light switch assembly

  • Stop light switch circuit

  • ECM

WIRING DIAGRAM

A01J5D5E06

INSPECTION PROCEDURE

PROCEDURE


  1. READ VALUE USING INTELLIGENT TESTER (STOP LIGHT SWITCH)


    1. Using the intelligent tester, read the Data List.

      Cruise Control
      Tester Display Measurement Item / Range Normal Condition Diagnostic Note
      Stop Light SW M-CPU Stop light switch signal (Main CPU) / ON or OFF

      ON: Brake pedal depressed

      OFF: Brake pedal released

      		 -
      OK
      Display changes according to brake pedal operation described in above table.

    NG

    INSPECT FUSE (STOP, IGN) Click here

    OK

    REPLACE ECM

  2. INSPECT FUSE (STOP, IGN)


    1. Disconnect the STOP and IGN fuses from the driver side junction block.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      STOP fuse Always Below 1 Ω
      IGN fuse

    NG

    INSPECT FUSE

    OK

  3. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. A01J392E01

      Remove the stop light switch.

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

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

    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY

    OK

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

    A01J3QJE11

    1. Disconnect the S14 stop light switch connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      S14-2 - Body ground Always 11 to 14 V
      S14-3 - Body ground Ignition switch ON

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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

    A01J3XOE01

    1. Disconnect the S14 stop light switch connector.

    2. Disconnect the E14 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      S14-1 - E14-15 (STP) Always Below 1 Ω
      S14-1 - Body ground Always 10 kΩ or higher
      S14-4 - E14-16 (ST1-) Always Below 1 Ω
      S14-4 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM