DYNAMIC RADAR 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.

The skid control ECU receives a signal from the driving support ECU and operates the brake control system. The skid control ECU operates the brake control system and at the same time illuminates the stop lights by operating the stop light control relay. The stop light switch assembly sends a brake pedal operation signal to the driving support ECU. After receiving the signal, the ECM performs fail-safe control by canceling the cruise control function.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

P0571

Stop Light Switch Circuit Malfunction

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

  • ECM

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

P0571

Stop Light Switch Circuit Malfunction

This trouble code is stored when the skid control ECU detects a malfunction in the stop light control relay circuit for 1 second while the dynamic radar cruise control is operating.

  • Vehicle stability control system

  • ECM

WIRING DIAGRAM

E195927E03

CAUTION / NOTICE / HINT

Note:

  • When the ECM is replaced with a new one, initialization must be performed (Click here).

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

PROCEDURE

  1. READ VALUE USING INTELLIGENT TESTER (STOP LIGHT SWITCH ASSEMBLY)

    1. Use the Data List to check if the stop light switch is functioning properly

      Click here

    Powertrain > Radar Cruise > Data List

    Tester Display

    Measurement Item

    Range

    Normal Condition

    Diagnostic Note

    Stp Light SW M-CPU

    Stop light switch (Main CPU) signal

    OFF or ON

    OFF: Brake pedal released

    ON: Brake pedal depressed

    -

    OK

    On screen, item changes between ON and OFF according to above chart.

    Result

    Result

    OK

    NG
    NG

    CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - BATTERY)Click here

    OK

  2. CHECK FOR DTC (VEHICLE STABILITY CONTROL SYSTEM)

    1. Check for DTCs

      Click here

      Powertrain > Radar Cruise > Trouble Codes

    OK

    Vehicle stability control system DTCs are not output.

    Result

    Result

    OK

    NG
    NG

    REPLACE VEHICLE STABILITY CONTROL SYSTEM

    Click here

    OK

  3. CHECK FOR DTC

    1. Clear the DTCs

      Click here

      Powertrain > Radar Cruise > Clear DTCs

    2. Perform the following to make sure the DTC detection conditions are met.

      Tip:

      If the detection conditions are not met, the system cannot detect the malfunction.

      1. Drive the vehicle at a speed of 50 km/h (30 mph) or more.

      2. Turn the cruise control switch on.

      3. Push the cruise control switch to -SET to activate cruise control.

    3. Check for DTCs

      Click here

      Powertrain > Radar Cruise > Trouble Codes

      OK

      DTC P0571 is not output.

    Result

    Result

    OK

    NG
    OK

    USE SIMULATION METHOD TO CHECK

    Click here

    NG

    REPLACE ECM

    Click here

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

    E182722C02

    *a

    Front view of wire harness connector(to Stop Light Switch Assembly)

    1. Disconnect the A5 stop light switch connector.

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      A5-2 - Body ground

      Always

      11 to 14 V

      A5-4 - Body ground

      Engine switch on (IG)

      11 to 14 V

      A5-4 - Body ground

      Engine switch off

      Below 1 V

    Result

    Result

    OK

    NG
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. INSPECT STOP LIGHT SWITCH ASSEMBLY

    E200528C03

    *1

    Pin

    *a

    Not Pushed

    *b

    Pushed

    1. Remove the stop light switch

      Click here

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

      Standard Voltage

      Tester Connection

      Switch Condition

      Specified Condition

      1 - 2

      Not pushed

      Below 8.3 Ω

      1 - 2

      Pushed

      10 kΩ or higher

      3 - 4

      Pushed

      Below 1.6 Ω

      3 - 4

      Not pushed

      10 kΩ or higher

    Result

    Result

    OK

    NG
    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY

    Click here

    OK

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

    1. Disconnect the A5 stop light switch connector.

    2. Disconnect the G44 and G45 ECM connectors.

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

    Standard Resistance

    Tester Connection

    Condition

    Specified Condition

    A5-3 - G44-8 (ST1-)

    Always

    Below 1 Ω

    A5-1 - G45-18 (STP)

    Always

    Below 1 Ω

    A5-3 - Body ground

    Always

    10 kΩ or higher

    A5-1 - Body ground

    Always

    10 kΩ or higher

    Result

    Result

    OK

    NG
    OK

    REPLACE ECM

    Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR