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 ECM. Upon receiving the signal, the ECM cancels the cruise control system.

DTC No. Detection Item DTC Detection Condition Trouble Area
P0571 Brake Switch "A" Circuit When voltage of STP terminal and that of ST1- terminal of ECM are less than 1 V for 0.5 seconds or more

  • Stop light switch assembly

  • ECM

  • Harness or connector

WIRING DIAGRAM

B003NK8E03

CAUTION / NOTICE / HINT

Note

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

PROCEDURE


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


    1. B003K5BC04
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the stop light switch assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A64-2 (GND) -Body ground Always Below 1 Ω

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A64-6 (B) - Body ground Ignition switch off Below 1 V
      Ignition switch ON 11 to 14 V
      A64-7 (B) - Body ground Always 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BATTERY AND BODY GROUND)

    OK

  2. CHECK HARNESS AND CONNECTOR (ECM - STOP LIGHT SWITCH ASSEMBLY)


    1. Disconnect the G50 ECM connector.

    2. Disconnect the A4 skid control ECU (brake actuator assembly) connector.

    3. Disconnect the A64 stop light switch assembly connector.

    4. for Automatic Transmission:


      1. w/ Smart Entry and Start System

        Disconnect the I4 shift lock control ECU connector.

      2. w/o Smart Entry and Start System

        Disconnect the I6 shift lock control ECU connector.

    5. w/ Smart Entry and Start System:

      Disconnect the G16 certification ECU (smart key ECU assembly) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G50-12 (ST1-) - A64-5 (L) Always Below 1 Ω
      G50-13 (STP) - A64-3 (L) Always Below 1 Ω
      G50-12 (ST1-) or A64-5 (L) - Body ground Always 10 kΩ or higher
      G50-13 (STP) or A64-3 (L) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

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

    OK

  3. CHECK STOP LIGHT SWITCH OUTPUT VOLTAGE


    1. B003RU9C06
      *a

      Front view of wire harness connector

      (to ECM)

      Disconnect the ECM connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      G50-12 (ST1-) - Body ground Ignition switch ON, brake pedal depressed 0 to 1.5 V
      Ignition switch ON, brake pedal released 7.5 to 14 V
      G50-13 (STP) - Body ground Brake pedal depressed 7.5 to 14 V
      Brake pedal released 0 to 1.5 V
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here