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SFI SYSTEM, Diagnostic DTC:P0724

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DTC Code DTC Name
P0724 Brake Switch "B" Circuit High
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DESCRIPTION

The stop light switch assembly is a duplex system that transmits 2 signals: STP and ST1-. These 2 signals are used by the ECM to monitor whether or not the brake system is working properly.

The purpose of this circuit is to prevent the engine from stalling while driving with the lock-up torque converter clutch on when the brakes are suddenly applied.

When the brake pedal is depressed, the stop light switch sends a signal to the ECM. Then the ECM cancels the operation of the lock-up clutch while braking is in progress.

DTC No. DTC Detection Condition Trouble Area
P0724 The stop light switch remains on even when vehicle is driven in a GO (30 km/h (18.63 mph) or more) and STOP (less than 3 km/h (1.86 mph)) pattern 5 times (2 trip detection logic).

  • Short in stop light switch signal circuit

  • Stop light switch assembly

  • ECM
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WIRING DIAGRAM

Refer to DTC P0504 (Click here).

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INSPECTION PROCEDURE

Tip:

  • Using the intelligent tester to read the Data List allows the values or states of switches, sensors, actuators and other items to be read without removing any parts. Reading the Data List information early in troubleshooting is one way to save diagnostic time.

  • Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was moving or stationary, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

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PROCEDURE


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    READ VALUE USING INTELLIGENT TESTER (STOP LIGHT SWITCH)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / Stop Light Switch.

    5. Read the value displayed on the tester when the brake pedal is depressed and released.

      OK
      Brake Pedal Display
      Released OFF
      Depressed ON

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    CHECK STOP LIGHT SWITCH ASSEMBLY INSTALLATION


    1. Check the stop light switch assembly installation (Click here).

      OK
      Stop light switch assembly is installed correctly.

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


    1. Disconnect the stop light switch assembly connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A85-2 (L) - G56-18 (STP) Always Below 1 Ω
      A85-4 (L) - G55-8 (ST1-) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A85-2 (L) or G56-18 (STP) - Body ground Always 10 kΩ or higher
      A85-4 (L) or G55-8 (ST1-) - Body ground Always 10 kΩ or higher

    4. Reconnect the stop light switch assembly connector.

    5. Reconnect the ECM connector.


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    INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. Inspect the stop light switch assembly (Click here).


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    CHECK FOR INTERMITTENT PROBLEMSClick here

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    SECURELY REINSTALL STOP LIGHT SWITCH ASSEMBLY

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    REPAIR OR REPLACE HARNESS OR CONNECTOR

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    REPLACE STOP LIGHT SWITCH ASSEMBLYClick here

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    REPLACE ECMClick here