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 and stores the DTC.

Tech Tips

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

Conditions (a), (b) and (c) continue for 5.0 seconds or more:

(2 trip detection logic)

(a) Ignition switch ON

(b) Brake pedal depressed

(c) STP signal off when ST1 signal is off

  • Short in stop light switch signal circuit

  • Stop light switch assembly

  • ECM
DTC Detection Drive Pattern
DTC No. Data List
P0504 Depress and release brake pedal with ignition switch ON
Related Data List
DTC No. Data List
P0504 Stop Light Switch

WIRING DIAGRAM

A005J0ME04

CAUTION / NOTICE / HINT

Note


  • When replacing the ECM, perform ECM Initialization and Registration Click here.

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

Tech Tips


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

  • Read freeze frame data using the intelligent tester. 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 intelligent tester.


    1. Connect the intelligent tester to the DLC3.

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

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

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

      Brake Pedal Operation Stop Light Switch
      Depressed ON
      Released OFF

PROCEDURE


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


    1. A005LKNE01

      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
      A76-1 (B)- Body ground Always 11 to 14 V
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

    3. Reconnect the stop light switch assembly connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR Click here

    OK

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


    1. A005JOLE01

      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 Switch Condition Specified Condition
      A76-5 (B)- Body ground Ignition switch ON 11 to 14 V
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

    4. Reconnect the stop light switch assembly connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR Click here

    OK

  3. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. Inspect the stop light switch assembly Click here.


    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    OK

  4. INSPECT ECM (STP AND ST1- VOLTAGE)


    1. A005LNXE01
      Text in Illustration
      *a Brake pedal operation
      *b Depressed
      *c Released
      *d

      Front view of 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 Specified Condition
      A59-28 (ST1-) - Body ground Released 7.5 to 14 V
      Depressed Below 1.5 V
      A59-29 (STP) - Body ground Released Below 1.5 V
      Depressed 7.5 to 14 V

    4. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR Click here

    OK

  5. REPLACE ECM


    1. Replace the ECM Click here.


    NEXT

    CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED Click here

  6. REPAIR OR REPLACE HARNESS OR CONNECTOR


    NEXT

    CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED Click here

  7. REPLACE STOP LIGHT SWITCH ASSEMBLY


    1. Replace the stop light switch assembly Click here.


    NEXT

  8. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the tester on.

    4. Clear the DTCs Click here.

    5. Turn the ignition switch to ON.

    6. Depress the brake pedal for 10 seconds or more.

    7. Enter the following menus: Powertrain / Engine and ECT / DTC / Pending.

    8. Confirm that the DTC is not output again.


    NEXT

    END