CRUISE CONTROL SYSTEM (except 1WW), Diagnostic DTC:P0571

DTC Code DTC Name
P0571 Stop Light Switch Circuit Malfunction

DESCRIPTION

When the brake pedal is depressed, the stop light switch assembly 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 assembly, and the ECM cancels cruise control.

When the brake pedal is released, positive voltage is applied to terminal ST1- of the ECM through the IGN fuse and the stop light switch assembly, and the ECM operates 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

  • Harness or connector

  • ECM

WIRING DIAGRAM

A01IUO0E05

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 ASSEMBLY - BATTERY AND BODY GROUND)


    1. A01IQ65E01
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the A55 switch connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A55-2 (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
      A55-6 (B) - Body ground Ignition switch ON 11 to 14 V
      Ignition switch off Below 1 V
      A55-7 (B) - Body ground Always 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH INPUT CIRCUIT)

    A01INLIE02
    Text in Illustration
    *1

    Front view of wire harness connector

    (to Stop Light Switch Assembly)

    1. Disconnect the A76 ECM connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A76-9 (STP) - Body ground Released Below 1.5 V
      Depressed 11 to 14 V
      A76-10 (ST1-) - Body ground Released 11 to 14 V
      Depressed Below 1.5 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK STOP LIGHT SWITCH ASSEMBLY


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

    2. Clear the DTC Click here.

    3. Check for the DTC Click here.

      OK
      DTC P0571 is not output.
      Result
      Result Proceed to
      OK A
      NG (for 1ZR-FAE) B
      NG (for 2ZR-FAE) C

    B

    REPLACE ECM Click here

    C

    REPLACE ECM Click here

    A

    END (STOP LIGHT SWITCH ASSEMBLY WAS DEFECTIVE)