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CRUISE CONTROL SYSTEM, Diagnostic DTC:P0571

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DTC Code DTC Name
P0571 Brake Switch "A" Circuit
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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 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 ECM through the STOP fuse and the stop light switch assembly, and the ECM turns the cruise control off.

DTC DTC Detection Condition Trouble Area
P0571 Voltage of STP signal and that of ST1- signal of ECM are less than 1 V for 0.5 seconds or more

  • Stop light switch assembly

  • Stop light switch circuit

  • STOP, IGN fuse

  • ECM
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WIRING DIAGRAM

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INSPECTION PROCEDURE

Note:

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

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PROCEDURE


  1. Click here

    INSPECT STOP LIGHT SWITCH ASSEMBLY (POWER SOURCE)


    1. A01CE90E01

      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
      A1-2 - Body ground Always 11 to 14 V

    3. Reconnect the stop light switch assembly connector.


  2. Click here

    INSPECT STOP LIGHT SWITCH ASSEMBLY (POWER SOURCE)


    1. A01CE90E01

      Disconnect the stop light switch assembly connector.

    2. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A1-4 - Body ground Engine switch on (IG) 11 to 14 V

    4. Reconnect the stop light switch assembly connector.


  3. Click here

    INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. A01CBYTE01

      Remove the stop light switch assembly (Click here).

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

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      1 - 2 Switch pin not pushed Below 1 Ω
      3 - 4 Switch pin not pushed 10 kΩ or higher
      1 - 2 Switch pin pushed 10 kΩ or higher
      3 - 4 Switch pin pushed Below 1 Ω

    3. Reinstall the stop light switch assembly (Click here).


  4. Click here

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


    1. A01CCE0E01

      Disconnect the ECM 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
      A8-36 (STP) - A1-1 Always Below 1 Ω
      A8-35 (ST1-) - A1-3 Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A8-36 (STP) or A1-1 - Body ground Always 10 kΩ or higher
      A8-35 (ST1-) or A1-3 - Body ground Always 10 kΩ or higher

    4. Reconnect the stop light switch assembly connector.

    5. Reconnect the ECM connector.

      Result
      Result Proceed to
      OK (for 2GR-FE) A
      OK (for 2AZ-FE) B
      NG C

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    REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH - BATTERY)

  6. Click here

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

  7. Click here

    REPLACE STOP LIGHT SWITCH ASSEMBLYClick here

  8. Click here

    REPLACE ECM (for 2AZ-FE)Click here

  9. Click here

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

  10. Click here

    REPLACE ECM (for 2GR-FE)Click here