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 control of vehicle speed by the cruise control system. The fail-safe function operates to enable normal driving even if there is a malfunction in the stop light signal circuit. The cancellation condition 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 system off.

DTC No. DTC Detection Condition Trouble Area
P0571 Voltage of STP signal and that of ST1- terminal 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

A0007JYE01

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 (POWER SOURCE CIRCUIT)


    1. A0007MRE01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the A28 stop light switch assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A28-1 (B) - A28-3 (GND) Power switch off 11 to 14 V
      A28-5 (B) - A28-3 (GND) Power switch on (IG) 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A28-3 (GND) - Body ground Always Below 1 Ω

    4. Reconnect the A28 stop light switch assembly connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. A0007QJE01
      Text in Illustration
      *a

      Component with harness connected

      (Stop Light Switch Assembly)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A28-2 (L) - A28-3 (GND) Power switch off, brake pedal not depressed Below 1 V
      Power switch off, brake pedal depressed 11 to 14 V
      A28-4 (L) - A28-3 (GND) Power switch on (IG), brake pedal not depressed 11 to 14 V
      Power switch on (IG), brake pedal depressed Below 1 V

    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 A33 power management control ECU connector.

    2. Disconnect the A28 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
      A33-23 (STP) - A28-2 (L) Always Below 1 Ω
      A33-7 (ST1-) - A28-4 (L) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A33-23 (STP) or A28-2 (L) - Body ground Always 10 kΩ or higher
      A33-7 (ST1-) or A28-4 (L) - Body ground Always 10 kΩ or higher

    4. Reconnect the A28 stop light switch assembly connector.

    5. Reconnect the A33 power management control ECU connector.


    OK

    REPLACE POWER MANAGEMENT CONTROL ECU Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR