ECD SYSTEM (w/ EGR Cooler), Diagnostic DTC:P0504

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

DESCRIPTION

In this system, the signals of the duplex type stop light switch (STP and ST1-) are used to judge whether the brake system is abnormal. When signals that indicate depressing and releasing the brake pedal are detected simultaneously, the ECM interprets this as a malfunction of the stop light switch.

Tech Tips

Normal conditions are shown in the table below.

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

Conditions (a), (b) and (c) continue for 0.5 seconds or more:

(1 trip detection logic)

(a) Ignition switch is ON

(b) Brake pedal is released

(c) STP signal is OFF when ST1- signal is OFF

  • Short in stop light switch signal circuit

  • Stop light switch

  • ECM

WIRING DIAGRAM

A01DXJUE03

INSPECTION PROCEDURE

Note

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

Tech Tips

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.

PROCEDURE


  1. CHECK OPERATION OF STOP LIGHT


    1. Check if the stop lights turn ON and OFF when the brake pedal is depressed and released.

      OK
      Stop lights turn ON and OFF normally.

    NG

    REPAIR OR REPLACE STOP LIGHT SWITCH CIRCUIT

    OK

  2. CHECK STP SIGNAL


    1. A01DVSPE14

      Connect the intelligent tester to the DLC3.

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

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

    4. Read the value.

      OK
      Brake Pedal Specified Condition
      Depressed STP signal ON
      Released STP signal OFF

    5. Measure the voltage of the ECM connectors.

      Standard voltage
      Tester Connection Brake Pedal Specified Condition
      ST1- (E6-14) - E1 (E7-7) Depressed Below 1.5 V
      ST1- (E6-14) - E1 (E7-7) Released 7.5 to 14 V

    OK

    CHECK FOR INTERMITTENT PROBLEMS Click here

    NG

  3. CHECK STOP LIGHT SWITCH ASSEMBLY


    1. A01DXWSE26

      Remove the stop light switch.

    2. Measure the resistance of the stop light switch.

      Standard resistance
      Tester Connection Switch Condition Specified Condition
      1 - 2 Pin not pushed Below 1 Ω
      3 - 4 Pin not pushed 10 kΩ or higher
      1 - 2 Pin pushed 10 kΩ or higher
      3 - 4 Pin pushed Below 1 Ω

    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY

    OK

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


    1. A01E28IE12

      Disconnect the S14 stop light switch connector.

    2. Disconnect the E6 ECM connector.

    3. Measure the resistance of the wire harness side connectors.

      Standard resistance (Check for open)
      Tester Connection Specified Condition
      S14-1 - STP (E6-15) Below 1 Ω
      S14-4 - ST1- (E6-14) Below 1 Ω
      Standard resistance (Check for short)
      Tester Connection Specified Condition
      S14-1 or STP (E6-15) - Body ground 10 kΩ or higher
      S14-4 or ST1- (E6-14) - Body ground 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM Click here