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 cruise control system control of vehicle speed. 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 cancels control of vehicle speed by the cruise control system.

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

A011WPHE01

INSPECTION PROCEDURE

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. Disconnect the stop light switch assembly connector.

      A011XGSE16

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A33-2 - Body ground Always 11 to 14 V
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - AUXILIARY BATTERY)

    OK

  2. INSPECT STOP LIGHT SWITCH ASSEMBLY (POWER SOURCE)

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

      A011XGSE16
      Standard Voltage
      Tester Connection Condition Specified Condition
      A33-4 - Body ground Power switch on (IG) 11 to 14 V
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - IG2 RELAY)

    OK

  3. INSPECT STOP LIGHT SWITCH ASSEMBLY

    1. Remove the stop light switch assembly Click here.

      A011Y36E05

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      1 - 2 Switch pin not pushed Below 0.1 Ω
      3 - 4 Switch pin not pushed 10 kΩ or higher
      1 - 2 Switch pin pushed 10 kΩ or higher
      3 - 4 Switch pin pushed Below 200 Ω
      Text in Illustration
      *a

      Component without harness connected

      (Stop Light Switch Assembly)
      *b Not pushed
      *c Pushed
    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    OK

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

    1. Disconnect the power management control ECU connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A39-23 (STP) - A33-1 Always Below 1 Ω
      A39-7 (ST1-) - A33-3 Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A39-23 (STP) or A33-1 - Body ground Always 10 kΩ or higher
      A39-7 (ST1-) or A33-3 - Body ground Always 10 kΩ or higher
    NG

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

    OK

    REPLACE POWER MANAGEMENT CONTROL ECU Click here