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 switch 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 circuit

  • Power management control ECU

WIRING DIAGRAM

A01NLOYE03

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 CIRCUIT)


    1. Disconnect the stop light switch assembly connector.

    2. A01NMCNE40
      Text in Illustration
      *1

      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
      A108-1 (B) - A108-3 (GND) Power switch off 11 to 14 V
      A108-5 (B) - A108-3 (GND) Power switch on (IG) 11 to 14 V
      Standard Resistance
      Tester Connection Condition Specified Condition
      A108-3 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. Connect the stop light switch assembly connector.

    2. A01NLW4E47
      Text in Illustration
      *1

      Component with harness connected

      (Stop Light Switch Assembly)

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A108-2 (L) - A108-3 (GND) Power switch off, brake pedal not depressed Below 1 V
      Power switch off, brake pedal depress 11 to 14 V
      A108-4 (L) - A108-3 (GND) Power switch on (IG), brake pedal not depress 11 to 14 V
      Power switch on (IG), brake pedal depress 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 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
      A108-2 (L) - A81-23 (STP) Always Below 1 Ω
      A108-4 (L) - A81-7 (ST1-) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A108-2 (L) or A81-23 (STP) - Body ground Always 10 kΩ or higher
      A108-4 (L) or A81-7 (ST1-) - Body ground Always 10 kΩ or higher
      Result
      Result Proceed to
      OK (for LHD) A
      OK (for RHD) B
      NG C

    B

    REPLACE POWER MANAGEMENT CONTROL ECU (for RHD) Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

    REPLACE POWER MANAGEMENT CONTROL ECU (for LHD) Click here