ECD SYSTEM(for Swirl Control Valve), Diagnostic DTC:P0504

DTC Code DTC Name
P0504 Brake Switch "A"/"B" Correlation

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 that the brake pedal is being depressed and released, are detected simultaneously, the ECM interprets this as a malfunction in the stop light switch and stores the DTC.

Tip:

The normal conditions are as shown in the table below.

Signal (ECM terminal)

Brake Pedal Released

In Transition

Brake Pedal Depressed

STP

OFF

ON

ON

ST1-

ON

ON

OFF

  • [OFF] denotes ground potential.

  • [ON] denotes battery potential (+B).

DTC No.

DTC Detection Condition

Trouble Area

P0504

When brake pedal is being depressed, STP signal and ST1- signal are OFF.

(2 trip detection logic)

  • Short in stop light switch signal circuit

  • Stop light switch assembly

  • ECM
Table 1. Related Data List

DTC No.

Data List

P0504

Stop Light Switch

WIRING DIAGRAM

A284195E02

CAUTION / NOTICE / HINT

Tip:

  • When the ECM must be replaced, before replacing the ECM, perform the "Learning Values Save" function using the GTS. Then after installing the new ECM, perform all of the initialization/registrations for the "Learning Values Write" function by following the instructions shown on the GTS display.

  • Read freeze frame data using the GTS. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, and other data from the time the malfunction occurred.

  • Stop light switch conditions can be checked using the GTS.

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

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

    5. Check Stop Light Switch when the brake pedal is depressed and released.

Brake Pedal Operation

Specified Condition

Depressed

ON

Released

OFF
Note:

  • When replacing the ECM, the ECM needs Registration and Initialization (Click here).

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

PROCEDURE

  1. CHECK ECM (STP AND ST1- VOLTAGE)

    U122124E02

    1. Disconnect the ECM connector.

    2. Turn the ignition switch to ON.

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

      Standard Voltage

      Tester Connection

      Brake Pedal Condition

      Specified Condition

      A76-10 (ST1-) - Body ground

      Released

      11 to 14 V

      Depressed

      0 to 3 V

      A76-48 (STP) - Body ground

      Released

      0 to 3 V

      Depressed

      11 to 14 V
      Table 2. Text in Illustration

      *a

      Brake Pedal Depressed

      *b

      Brake Pedal Released

      *c

      Front view of wire harness connector

      (to ECM)

    CHECK WHETHER DTC OUTPUT RECURSClick here

  2. CHECK STOP LIGHT SWITCH ASSEMBLY (TERMINAL B VOLTAGE)

    1. U124048E02

      Disconnect the stop light switch connector.

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

      Standard Voltage

      Tester Connection

      Switch Condition

      Specified Condition

      A55-7 (B) - Body ground

      Always

      11 to 14 V

      A55-6 (B) - Body ground

      Ignition switch ON

      11 to 14 V

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      A55-2 (GND) - Body ground

      Always

      Below 1 Ω
      Table 3. Text in Illustration

      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

    REPAIR OR REPLACE HARNESS OR CONNECTORClick here

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

    1. 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

      Tester Connection

      Condition

      Specified Condition

      A55-5 (L) - A76-10 (ST1-)

      Always

      Below 1 Ω

      A55-3 (L) - A76-48 (STP)

      Always

      Below 1 Ω

      A55-5 (L) or A76-10 (ST1-) - Body ground

      Always

      10 kΩ or higher

      A55-3 (L) or A76-48 (STP) - Body ground

      Always

      10 kΩ or higher

    REPAIR OR REPLACE HARNESS OR CONNECTORClick here

  4. REPLACE STOP LIGHT SWITCH ASSEMBLY

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

    CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIREDClick here

  5. CHECK WHETHER DTC OUTPUT RECURS

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON and turn the GTS on.

    3. Clear the DTCs (Click here).

    4. Turn the ignition switch off and wait for 60 seconds or more [A].

    5. Start the engine and wait for 15 seconds or more [B].

    6. Release and depress the brake pedal [C].

    7. Repeat [A] through [C] for the number of trips detected.

    8. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

    9. Confirm that the DTC is not output again.

      OK

      DTC is not output again.

    END

    REPLACE ECMClick here

  6. REPAIR OR REPLACE HARNESS OR CONNECTOR

    1. Repair or replace the harness or connector.

    CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIREDClick here

  7. REPLACE ECM

    1. Replace the ECM (Click here).

  8. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON and turn the GTS on.

    3. Clear the DTCs (Click here).

    4. Turn the ignition switch off and wait for 60 seconds or more [A].

    5. Start the engine and wait for 15 seconds or more [B].

    6. Release and depress the brake pedal [C].

    7. Repeat [A] through [C] for the number of trips detected.

    8. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

    9. Confirm that the DTC is not output again.

    END