CRUISE CONTROL SYSTEM(for 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 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 assembly

  • Harness or connector

  • ECM

WIRING DIAGRAM

E314988E01

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 ASSEMBLY - BATTERY AND BODY GROUND)

    1. U124045E01

      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
    Table 1. Text in Illustration

    *1

    Front view of wire harness connector

    (to Stop Light Switch Assembly)

    REPAIR OR REPLACE HARNESS OR CONNECTOR

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

    U124146E01

    1. Disconnect the A76 ECM connector.

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      A76-10 (ST1-) - Body ground

      Released

      11 to 14 V

      Depressed

      0 to 3 V

      A76-48 (STP) - Body ground

      Released

      0 to 3 V

      Depressed

      11 to 14 V
    Table 2. Text in Illustration

    *1

    Front view of wire harness connector

    (to ECM)

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  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 DTCs (Click here).

    3. Check for DTCs (Click here).

      OK

      DTC P0571 is not output.

    END (STOP LIGHT SWITCH ASSEMBLY WAS DEFECTIVE)

    REPLACE ECM

    (Click here)