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 the cruise control system. Even if there is a malfunction in the stop light signal circuit while the cruise control is in operation, normal driving is maintained due to a fail-safe function. Cruise control is canceled when positive battery voltage is applied to terminal STP.

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

  • ECM

WIRING DIAGRAM

A003ENVE02

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. A003BWSE01

      Disconnect the A1 switch connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A1-2 - Body ground Always 11 to 14 V
      A1-3 - Body ground Ignition switch ON 11 to 14 V
      Ignition switch off Below 1 V

    NG
    OK
  2. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. A003ASWE01

      Remove the stop light switch Click here.

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

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

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

    A003B9PE02
    Text in Illustration
    *1

    Front view of wire harness connector

    (to Stop Light Switch)

    *2

    Front view of wire harness connector

    (to ECM)


    1. Disconnect the A1 switch connector.

    2. Disconnect the A40 ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A1-4 - A40-34 (ST1-) Always Below 1 Ω
      A1-1 - A40-35 (STP)
      A1-4 - Body ground Always 10 kΩ or higher
      A1-1 - Body ground
      Result
      Result Proceed to
      OK (for 1AD-FTV) A
      OK (for 2AD-FTV) B
      OK (for 2AD-FHV) C
      NG D

    B
    C
    D
    A