ECD SYSTEM, Diagnostic DTC:P0504

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

DESCRIPTION

The stop light switch assembly 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 assembly and stores the DTC.

Tech Tips

The normal conditions are as shown in the table below.

Signals (ECM Terminal) Brake Pedal Released In Transition Brake Pedal Depressed
STP OFF ON ON
ST1- ON ON OFF
DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory
P0504 Brake Switch "A" / "B" Correlation

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

(a) Ignition switch ON.

(b) Brake pedal is released.

(c) The STP signal is off when the ST1- signal is off, or the STP signal is on when the ST1- signal is on.

  • Open or short in stop light switch assembly signal circuit

  • Stop light switch assembly

  • ECM

 - DTC stored
Related Data List
DTC No. Data List
P0504 Stop Light Switch

CONFIRMATION DRIVING PATTERN

DTC No. DTC Detection Drive Pattern
P0504 Release and depress brake pedal with ignition switch ON

WIRING DIAGRAM

A01QU7LE14
*a from IG2 Relay
*b STOP
*c from Battery
*d Stop Light Switch

CAUTION / NOTICE / HINT

Note


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

  • After replacing the ECM, the new ECM needs registration (Click here ) and initialization Click here.

Tech Tips


  • 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 / 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

PROCEDURE


  1. CHECK TERMINAL VOLTAGE (POWER SOURCE OF STOP LIGHT SWITCH ASSEMBLY)


    1. A01QPGSC06
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the stop light switch assembly 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 Condition Specified Condition
      A5-2 - Body ground Always 11 to 14 V
      A5-4 - Body ground Ignition switch ON 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    GO TO STEP 5 Click here

    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 ECM (STP AND ST1- VOLTAGE)


    1. A01QSZEC02
      *a Brake Pedal Depressed
      *b Brake Pedal Released
      *c

      Front view of wire harness connector

      (to ECM)

      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 Switch Condition
      A61-34 (ST1-) - Body ground Released 7.5 to 14 V
      Depressed Below 1.5 V
      A61-35 (STP) - Body ground Released Below 1.5 V
      Depressed 7.5 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR Click here

    OK

  4. REPLACE ECM


    1. Replace the ECM.

      Click here

      Result
      Proceed to
      NEXT

    NEXT

    GO TO STEP 6 Click here

  5. REPAIR OR REPLACE HARNESS OR CONNECTOR


    1. Repair or replace the harness or connector.

      Result
      Proceed to
      NEXT

    NEXT

  6. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED


    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Clear the DTCs.


      Powertrain > Engine > Clear DTCs

    5. Turn the ignition switch off.

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

    7. Release and depress the brake pedal.

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


      Powertrain > Engine > Trouble Codes

    9. Confirm that the DTC is not output again.

      Result
      Proceed to
      NEXT

    NEXT

    END

  7. REPLACE STOP LIGHT SWITCH ASSEMBLY


    1. Replace the stop light switch assembly.

      Click here

      Result
      Proceed to
      NEXT

    NEXT

    GO TO STEP 6 Click here