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. When the ECM receives this signal, it cancels control of vehicle speed by the cruise control system. The fail-safe function operates to enable normal driving even if there is a malfunction in the stop light switch assembly signal circuit. The cancellation condition occurs when voltage is applied to terminal STP. When the brake pedal is depressed, voltage is applied to terminal STP of the ECM through the STOP fuse and the stop light switch assembly, and the ECM cancels control of vehicle speed by the cruise control system.

DTC No. Detection Item DTC Detection Condition Trouble Area
P0571 Brake Switch "A" Circuit When the ignition switch ON and the cruise control system is operating, the voltage of the STP and ST1- terminals of the ECM are less than 1 V for 0.5 seconds or more.

  • Stop light switch assembly

  • Harness or connector

  • ECM

WIRING DIAGRAM

B001G0RE09
for 1GR-FE, Automatic Transmission
*a from IG2 Relay
*b from Battery
*c STOP
*d Stop Light Switch Assembly
B001IIGE04
for 1GR-FE, Manual Transmission
*a from IG2 Relay
*b from Battery
*c STOP
*d Stop Light Switch Assembly
B001G0RE10
for 2TR-FE
*a from IG2 Relay
*b from Battery
*c STOP
*d Stop Light Switch Assembly
B001G0RE11
for 1KD-FTV
*a from IG2 Relay
*b from Battery
*c STOP
*d Stop Light Switch Assembly
B001G0RE12
for 1GD-FTV
*a from IG2 Relay
*b from Battery
*c STOP
*d Stop Light Switch Assembly

CAUTION / NOTICE / HINT

Note


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

  • Before replacing the ECM, refer to Service Bulletin.

Tech Tips

After performing repairs on the vehicle, clear the DTCs and perform the following procedure to check that DTCs are not output.


  1. Turn the ignition switch ON.

  2. Turn the cruise control system on using the cruise control main switch (ON-OFF button).

  3. Depress the brake pedal for 0.5 seconds or more.

PROCEDURE


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


    1. B001GI2C05
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the A99 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
      A99-2 (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
      A99-7 (B) - Body ground Always 11 to 14 V
      A99-6 (B) - Body ground Ignition switch ON 11 to 14 V
      A99-6 (B) - Body ground Ignition switch off Below 1 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. Inspect the stop light switch assembly.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    OK

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


    1. for 1GR-FE, Automatic Transmission


      1. Disconnect the A99 switch connector.

      2. Disconnect the F56 ECM connectors.

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

        Standard Resistance
        Tester Connection Condition Specified Condition
        F56-34 (ST1-) - A99-5 (L) Always Below 1 Ω
        F56-35 (STP) - A99-3 (L) Always Below 1 Ω
        F56-34 (ST1-) or A99-5 (L) - Body ground Always 10 kΩ or higher
        F56-35 (STP) or A99-3 (L) - Body ground Always 10 kΩ or higher

    2. for 1GR-FE, Manual Transmission


      1. Disconnect the A99 switch connector.

      2. Disconnect the G55 and G56 ECM connectors.

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

        Standard Resistance
        Tester Connection Condition Specified Condition
        G55-8 (ST1-) - A99-5 (L) Always Below 1 Ω
        G56-18 (STP) - A99-3 (L) Always Below 1 Ω
        G55-8 (ST1-) or A99-5 (L) - Body ground Always 10 kΩ or higher
        G56-18 (STP) or A99-3 (L) - Body ground Always 10 kΩ or higher

    3. for 2TR-FE


      1. Disconnect the A99 switch connector.

      2. Disconnect the G180 ECM connectors.

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

        Standard Resistance
        Tester Connection Condition Specified Condition
        G180-11 (ST1-) - A99-5 (L) Always Below 1 Ω
        G180-10 (STP) - A99-3 (L) Always Below 1 Ω
        G180-11 (ST1-) or A99-5 (L) - Body ground Always 10 kΩ or higher
        G180-10 (STP) or A99-3 (L) - Body ground Always 10 kΩ or higher

    4. for 1KD-FTV


      1. Disconnect the A99 switch connector.

      2. Disconnect the G57 ECM connector.

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

        Standard Resistance
        Tester Connection Condition Specified Condition
        G57-9 (ST1-) - A99-5 (L) Always Below 1 Ω
        G57-8 (STP) - A99-3 (L) Always Below 1 Ω
        G57-9 (ST1-) or A99-5 (L) - Body ground Always 10 kΩ or higher
        G57-8 (STP) or A99-3 (L) - Body ground Always 10 kΩ or higher

    5. for 1GD-FTV


      1. Disconnect the A99 switch connector.

      2. Disconnect the G185 ECM connector.

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

        Standard Resistance
        Tester Connection Condition Specified Condition
        G185-12 (ST1-) - A99-5 (L) Always Below 1 Ω
        G185-13 (STP) - A99-3 (L) Always Below 1 Ω
        G185-12 (ST1-) or A99-5 (L) - Body ground Always 10 kΩ or higher
        G185-13 (STP) or A99-3 (L) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECM for 1GR-FE: Click here
    REPLACE ECM for 1KD-FTV: Click here
    REPLACE ECM for 1GD-FTV: Click here
    REPLACE ECM for 2TR-FE: Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR