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.

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.

When the brake pedal is released, positive voltage is applied to terminal ST1- of the ECM through the LH-IG2 fuse and the stop light switch, and the ECM operates the cruise control.

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

  • Stop light switch assembly

  • Stop light switch circuit

  • ECM

  • Harness or connector

WIRING DIAGRAM

A01FDMNE01

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)

    A01FH0AE02
    Text in Illustration
    *a

    Front view of wire harness connector

    (to Stop Light Switch Assembly)

    1. Disconnect the stop light switch assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A5-1 (B) - Body ground Always 11 to 14 V
      A5-5 (B) - Body ground Engine switch on (IG)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A5-3 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Disconnect the A19 ECM connector.

    2. Disconnect the A5 stop light switch assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A19-12 (ST1-) - A5-4 (L) Always Below 1 Ω
      A19-13 (STP) - A5-2 (L)
      A19-12 (ST1-) - Body ground Always 10 kΩ or higher
      A19-13 (STP) - Body ground

    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. Recheck for DTC Click here.

      OK
      DTC P0571 is not output.
      Result
      Result Proceed to
      OK A
      NG (for 2GR-FSE) B
      NG (for 4GR-FSE) C

    B

    REPLACE ECM Click here

    C

    REPLACE ECM Click here

    A

    END (STOP LIGHT SWITCH ASSEMBLY IS DEFECTIVE)