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.

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, and the ECM operates 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

  • Harness or connector

  • ECM

WIRING DIAGRAM

A004RIIE17
*a from IG2 Relay
*b from Battery
*c STOP
*d Stop Light Switch

CAUTION / NOTICE / HINT

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 AND BODY GROUND)


    1. A004U6AE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to stop light switch)

      Disconnect the stop light switch connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A67-2 (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
      A67-6 (B) - Body ground Ignition switch ON 11 to 14 V
      Ignition switch off Below 1 V
      A67-7 (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)

    A004TBWE02
    Text in Illustration
    *a

    Front view of wire harness connector

    (to ECM)

    1. Disconnect the ECM connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A83-10 (ST1-) - Body ground Ignition switch ON, brake pedal released 7.5 to 14 V
      Ignition switch ON, brake pedal depressed 0 to 1.5 V
      A83-48 (STP) - Body ground Brake pedal released 0 to 1.5 V
      Brake pedal depressed 7.5 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK STOP LIGHT SWITCH


    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
      DTC is not output A
      DTC is output (for 1WW) B
      DTC is output (for 2WW) C

    A

    END (STOP LIGHT SWITCH WAS DEFECTIVE)

    B

    REPLACE ECM Click here

    C

    REPLACE ECM Click here