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 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

A01JCT4E08

INSPECTION PROCEDURE

Note

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

PROCEDURE


  1. CHECK WIRE HARNESS AND CONNECTOR (STOP LIGHT SWITCH POWER SOURCE)


    1. Disconnect the stop light switch assembly connector.

    2. A01JCQ1E10
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A67-1 (B) - A67-3 (GND) Power switch off 11 to 14 V
      A67-5 (B) - A67-3 (GND) Power switch on (IG) 11 to 14 V
      Standard Resistance
      Tester Connection Condition Specified Condition
      A67-3 (GND) - ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. INSPECT STOP LIGHT SWITCH ASSEMBLY (POWER SOURCE)


    1. Reconnect the stop light switch assembly connector.

    2. A01JCFXE08
      Text in Illustration
      *a

      Component with harness connected

      (to Stop Light Switch Assembly)

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A67-2 (L) - A67-3 (GND) Power switch off , brake pedal not depressed Below 1 V
      Power switch off , brake pedal depressed 11 to 14 V
      A67-4 (L) - A67-3 (GND) Power switch off , brake pedal not depressed Below 1V
      Power switch off , brake pedal depressed 11 to 14 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 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
      A22-23 (STP) - A67-4 (L) Always Below 1 Ω
      A22-7 (ST1-) - A67-2 (L) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A22-23 (STP) or A67-4 (L) - Body ground Always 10 kΩ or higher
      A22-7 (ST1-) or A67-2 (L) - Body ground Always 10 kΩ or higher

    NG

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

    OK

    REPLACE POWER MANAGEMENT CONTROL ECU Click here