CRUISE CONTROL SYSTEM, Diagnostic DTC:P0571

DTC Code DTC Name
P0571 Brake Switch "A" Circuit

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 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 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 assembly, 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 IGN fuse and the stop light switch assembly, and the ECM operates the cruise control.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

P0571

Brake Switch "A" Circuit

When voltage of STP terminal and that of ST1- terminal of ECM are less than 1 V for 0.5 seconds or more

  • Stop light switch assembly

  • ECM

  • Harness or connector

WIRING DIAGRAM

E288572E34
E288572E35
E288572E39
E288572E37

CAUTION / NOTICE / HINT

Note:

Inspect the fuses for circuits related to this system before performing the following procedure.

PROCEDURE

  1. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BATTERY)

    1. Disconnect the stop light switch assembly connector.

    2. E270087C07

      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      A77-7 (B) - Body ground

      Always

      11 to 14 V

      A77-6 (B) - Body ground

      Ignition switch ON

      11 to 14 V

      A77-6 (B) - Body ground

      Ignition switch off

      Below 1 V

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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

    1. Disconnect the ECM connector.

    2. E217720C22

      *a

      Front view of wire harness connector

      (to ECM)

      for 2AR-FE:

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      A62-24 (ST1-) - Body ground

      Ignition switch ON, brake pedal depressed

      Below 1.5 V

      Ignition switch ON, brake pedal released

      7.5 to 14 V

      A62-11 (STP) - Body ground

      Brake pedal depressed

      7.5 to 14 V

      Brake pedal released

      Below 1.5 V
    3. E217720C23

      *a

      Front view of wire harness connector

      (to ECM)

      for 3ZR-FAE, 3ZR-FE:

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      A62-10 (ST1-) - Body ground

      Ignition switch ON, brake pedal depressed

      Below 1.5 V

      Ignition switch ON, brake pedal released

      7.5 to 14 V

      A62-9 (STP) - Body ground

      Brake pedal depressed

      7.5 to 14 V

      Brake pedal released

      Below 1.5 V
    4. E207340C03

      *a

      Front view of wire harness connector

      (to ECM)

      for 2AD-FHV, 2AD-FTV:

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      A61-34 (ST1-) - Body ground

      Ignition switch ON, brake pedal depressed

      0 to 1.5 V

      Ignition switch ON, brake pedal released

      7.5 to 14 V

      A61-35 (STP) - Body ground

      Brake pedal depressed

      7.5 to 14 V

      Brake pedal released

      0 to 1.5 V
    5. E217720C24

      *a

      Front view of wire harness connector

      (to ECM)

      for 2WW:

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      A62-10 (ST1-) - Body ground

      Ignition switch ON, brake pedal depressed

      0 to 1.5 V

      Ignition switch ON, brake pedal released

      7.5 to 14 V

      A62-48 (STP) - Body ground

      Brake pedal depressed

      7.5 to 14 V

      Brake pedal released

      0 to 1.5 V

    Result

    Proceed to

    OK

    NG
    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 DTCs.

      Click here

      1. for 2AD-FTV, 2AD-FHV:

        Powertrain > Cruise Control > Clear DTCs

      2. for 2AR-FE, 3ZR-FE, 3ZR-FAE:

        Powertrain > Cruise Control > Clear DTCs

      3. for 2WW:

        Powertrain > Cruise Control > Clear DTCs

    3. Check for DTCs.

      Click here

      1. for 2AD-FTV, 2AD-FHV:

        Powertrain > Cruise Control > Trouble Codes

      2. for 2AR-FE, 3ZR-FE, 3ZR-FAE:

        Powertrain > Cruise Control > Trouble Codes

      3. for 2WW:

        Powertrain > Cruise Control > Trouble Codes

    Result

    Result

    Proceed to

    DTC is not output

    A

    DTC P0571 is output

    B
    A

    END (STOP LIGHT SWITCH ASSEMBLY WAS DEFECTIVE)

    B

    REPLACE ECM

    for 2AD-FHV:Click here

    for 2AD-FTV:Click here

    for 2AR-FE:Click here

    for 3ZR-FAE:Click here

    for 3ZR-FE:Click here

    for 2WW:Click here