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. Upon receiving the signal, the ECM cancels cruise control. Even if there is a malfunction in the stop light signal circuit while cruise control is in operation, normal driving is maintained due to a fail-safe function.

When the brake pedal is depressed, positive voltage is applied to terminal STP of the ECM through the STOP fuse and stop light switch, and the ECM cancels cruise control.

DTC Code DTC Detection Condition Trouble Area
P0571 The voltages of terminals ST1- and STP of the ECM are both below 1 V for 0.5 seconds or more.

  • Stop light switch circuit

  • Stop light switch assembly

  • ECM

WIRING DIAGRAM

A01DSV8E06
A01DSV8E07
A01DSV8E05

INSPECTION PROCEDURE

Note

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

PROCEDURE


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


    1. A01DMNDE07
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the A85 switch connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A85-1 (B) - Body ground Always 11 to 14 V
      A85-5 (B) - Body ground Ignition switch ON 11 to 14 V
      Ignition switch off Below 1 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A85-3 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. for 1GR-FE


      1. Disconnect the A85 switch connector.

      2. Disconnect the G55 and G56 ECM connectors.

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

        Standard Resistance
        Tester Connection Switch Condition Specified Condition
        A85-4 (L) - G55-8 (ST1-) Always Below 1 Ω
        A85-2 (L) - G56-18 (STP)
        A85-4 (L) - Body ground Always 10 kΩ or higher
        A85-2 (L) - Body ground

    2. for 2TR-FE


      1. Disconnect the A85 switch connector.

      2. Disconnect the G59 and G60 ECM connectors.

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

        Standard Resistance
        Tester Connection Switch Condition Specified Condition
        A85-4 (L) - G59-8 (ST1-) Always Below 1 Ω
        A85-2 (L) - G60-18 (STP)
        A85-4 (L) - Body ground Always 10 kΩ or higher
        A85-2 (L) - Body ground

    3. for 1KD-FTV


      1. Disconnect the A85 switch connector.

      2. Disconnect the G57 ECM connector.

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

        Standard Resistance
        Tester Connection Switch Condition Specified Condition
        A85-4 (L) - G57-9 (ST1-) Always Below 1 Ω
        A85-2 (L) - G57-8 (STP)
        A85-4 (L) - Body ground Always 10 kΩ or higher
        A85-2 (L) - Body ground

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK STOP LIGHT SWITCH ASSEMBLY


    1. Temporarily replace the stop light switch with a new or normally functioning one Click here.

    2. Clear the DTCs Click here.

    3. Check for DTCs Click here.

      Result
      Result Proceed to
      OK A
      NG (for 1GR-FE) B
      NG (for 2TR-FE) C
      NG (for 1KD-FTV) D

    B

    REPLACE ECM Click here

    C

    REPLACE ECM Click here

    D

    REPLACE ECM Click here

    A

    END (STOP LIGHT SWITCH IS DEFECTIVE)