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 power management control ECU. When the power management control ECU receives this signal, it cancels the cruise control. The fail-safe function operates to enable normal driving even if there is a malfunction in the stop light signal circuit. Cruise control cancellation occurs when voltage is applied to terminal STP. When the brake is applied, voltage is normally applied to terminal STP of the power management control ECU through the STOP fuse and the stop light switch assembly, and the power management control ECU turns the cruise control off.

DTC No. DTC Detection Condition Trouble Area
P0571 Voltage of STP signal and that of ST1- signal of power management control ECU are less than 1 V for 0.5 seconds or more

  • Stop light switch assembly

  • Stop light switch assembly circuit

  • Power management control ECU

WIRING DIAGRAM

A004Y99E12

CAUTION / NOTICE / HINT

Note

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

PROCEDURE


  1. INSPECT STOP LIGHT SWITCH ASSEMBLY (POWER SOURCE)


    1. A004VS9E01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the stop light switch assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A74-1 (B)- A74-3 (GND) Power switch off 11 to 14 V
      A74-5 (B)- A74-3 (GND) Power switch on (IG) 11 to 14 V
      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      A74-3 (GND) - Body ground Always Below 1 Ω

    3. Reconnect the stop light switch assembly connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. Remove the stop light switch assembly Click here.

    2. Inspect the stop light switch assembly Click here.


    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU - STOP LIGHT SWITCH ASSEMBLY)


    1. Disconnect the power management control ECU connector.

    2. Disconnect the stop light switch assembly connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A20-23 (STP) - A74-2 (L) Always Below 1 Ω
      A20-7 (ST1-) - A74-4 (L) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A20-23 (STP) or A74-2 (L) - Body ground Always 10 kΩ or higher
      A20-7 (ST1-) or A74-4 (L) - Body ground Always 10 kΩ or higher

    4. Reconnect the stop light switch assembly connector.

    5. Reconnect the power management control ECU connector.


    OK

    REPLACE POWER MANAGEMENT CONTROL ECU Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER MANAGEMENT CONTROL ECU - STOP LIGHT SWITCH ASSEMBLY)