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SFI SYSTEM, Diagnostic DTC:P0504, P0724

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DTC Code DTC Name
P0504 Brake Switch "A" / "B" Correlation
P0724 Brake Switch "B" Circuit High
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DESCRIPTION

The stop light switch is a duplex system that transmits two signals: STP and ST1-. These two signals are used by the ECM to monitor whether or not the brake system is working properly. If the signals, which indicate the brake pedal is being depressed or released, are detected simultaneously, the ECM interprets this as a malfunction in the stop light switch and sets the DTC.

Tip:

The normal conditions are as shown in the table below. The signals can be read using the intelligent tester.

Signal Brake Pedal Released In Transition Brake Pedal Depressed
STP OFF ON ON
ST1- ON ON OFF
DTC No. DTC Detection Conditions Trouble Areas
P0504

Conditions (a), (b) and (c) continue for 0.5 seconds or more (1 trip detection logic):

(a) Ignition switch on (IG)

(b) Brake pedal released

(c) STP signal OFF when ST1- signal OFF

  • Short in stop light switch signal circuit

  • STOP fuse

  • Stop light switch

  • ECM
P0724 The stop light switch remains ON even when the vehicle is driven in a STOP (less than 2 mph (3 km/h)) and GO (30 km/h (19 mph) or more) fashion 5 times. (2 trip detection logic)

  • Short in stop light switch signal circuit

  • Stop light switch

  • ECM
A017ERHE06
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WIRING DIAGRAM

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INSPECTION PROCEDURE

Tip:

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 running or stopped, 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


  1. Click here

    CHECK OPERATION OF STOP LIGHT


    1. Check whether the stop lights turn on and off normally when the brake pedal is depressed and released.

      OK
      Stop lights turn on when brake pedal is depressed.

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    INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. A017F5ME24

      Remove the stop light switch assembly.

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

      Standard resistance
      Switch Position Tester Connection Specified Condition
      Switch pin free 1 - 2 Below 1 Ω
      Switch pin free 3 - 4 10 kΩ or higher
      Switch pin pushed in 1 - 2 10 kΩ or higher
      Switch pin pushed in 3 - 4 Below 1 Ω

    3. Reinstall the stop light switch assembly.


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    READ VALUE USING INTELLIGENT TESTER (STP SIGNAL AND ST1 - VOLTAGE)


    1. A017D4OE14

      Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch on (IG) and turn the tester on.

    3. Select the following menu items: Powertrain Engine and ECT / Data List / Stop Light Switch.

    4. Check the STP signal when the brake pedal is depressed and released.

      Standard
      Brake Pedal Operation Specified Condition
      Depressed STP signal ON
      Released STP signal OFF

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

      Standard voltage
      Tester Connection Brake Pedal Operation Specified Condition
      D31-16 (ST1-) - B3-1 (E1) Depressed Below 1.5 V
      D31-16 (ST1-) - B3-1 (E1) Released 7.5 to 14 V

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    CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - ECM)


    1. A017CN9E03

      Disconnect the stop light switch 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
      A20-1 (Stop light switch) - D31-15 (STP) Always Below 1 Ω
      A20-4 (Stop light switch) - D31-16 (ST1-) Always Below 1 Ω
      Standard resistance (Check for short)
      Tester Connection Condition Specified Condition
      A20-1 (Stop light switch) or D31-15 (STP) - Body ground Always 10 kΩ or higher
      A20-4 (Stop light switch) or D31-16 (ST1-) - Body ground Always 10 kΩ or higher

    4. Reconnect the stop light switch connector.

    5. Reconnect the ECM connector.


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    REPLACE ECMClick here

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    REPLACE STOP LIGHT SWITCH ASSEMBLY

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    GO TO LIGHTING SYSTEM (STOP LIGHT SYSTEM)Click here

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    CHECK FOR INTERMITTENT PROBLEMSClick here

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    REPAIR OR REPLACE HARNESS OR CONNECTOR