CRUISE CONTROL SYSTEM, Diagnostic DTC:P0571

DTC Code DTC Name
P0571 Stop Light Switch Circuit Malfunction

DESCRIPTION

When the brake pedal is depressed, the stop light switch sends a signal to the power management control ECU.

Receiving the signal, the power management control ECU cancels the cruise control system. Even if there is a malfunction in the stop light signal circuit while the cruise control is in operation, normal driving is maintained due to a fail-safe function. Cruise control is canceled when positive battery voltage is applied to terminal STP.

When the brake pedal is depressed, positive voltage is applied to terminal STP of the power management control ECU through the STOP fuse and the stop light switch, and the power management control ECU cancels the cruise control.

When the brake pedal is released, positive voltage is applied to terminal ST1- of the power management control ECU through the LH-IG2 fuse and the stop light switch, and the power management control ECU operates the cruise control.

DTC Code DTC Detection Condition Trouble Area
P0571 Trouble code is output when voltages of terminals ST1- and STP of power management control ECU are both below 1 V for 0.5 seconds or more.

  • Stop light switch assembly

  • Stop light switch circuit

  • Power management control ECU

  • Harness or connector

WIRING DIAGRAM

A000SFLE01

CAUTION / NOTICE / HINT

Note


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

  • If the power management control ECU is replaced, refer to the Service Bulletin.

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BATTERY AND BODY GROUND)

    A000P4AE02
    Text in Illustration
    *a

    Front view of wire harness connector

    (to Stop Light Switch Assembly)

    1. Disconnect the 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
      A5-1 (B) - Body ground Always 11 to 14 V
      A5-5 (B) - Body ground Power switch on (IG)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A5-3 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Disconnect the A35 and N92 power management control ECU connectors.

    2. Disconnect the A5 stop light switch assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A35-6 (ST1-) - A5-4 (L) Always Below 1 Ω
      N92-10 (STP) - A5-2 (L)
      A35-6 (ST1-) - Body ground Always 10 kΩ or higher
      N92-10 (STP) - Body ground

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK STOP LIGHT SWITCH ASSEMBLY


    1. Temporarily replace the stop light switch assembly with a new or normally functioning one Click here.

    2. Clear the DTC Click here.

    3. Recheck for DTC Click here.

      OK
      DTC P0571 is not output.

    OK

    END (STOP LIGHT SWITCH ASSEMBLY IS DEFECTIVE)

    NG

    REPLACE POWER MANAGEMENT CONTROL ECU Click here