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

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

DESCRIPTION

The signals of the stop light switch's duplex system (STP and ST1-) are used to judge whether the brake system is abnormal or not. When the signals of depressing and releasing the brake pedal are detected simultaneously, the ECM interprets this as a malfunction of the stop light switch.

Tech Tips

Normal condition is 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 (1), (2) and (3) continue for 0.5 seconds or more:


  1. Ignition switch is ON

  2. Brake pedal is released

  3. STP signal is OFF when ST1- signal is OFF

  • Short in stop light switch signal circuit

  • Stop light switch

  • ECM

WIRING DIAGRAM

A01DZ6BE03

INSPECTION PROCEDURE

Tech Tips

Read freeze frame data using the intelligent tester. Freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, freeze frame data can help determine if the vehicle was running or stopped, if the engine was warmed up or not, and other data from the time the malfunction occurred.

Note

If the ECM is replaced, the new ECM needs initialization Click here.

PROCEDURE


  1. CHECK STOP LIGHT (OPERATION)


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

      OK
      Stop lights turn ON and OFF when brake pedal is depressed and released.

    NG

    REPAIR OR REPLACE STOP LIGHT SWITCH CIRCUIT

    OK

  2. READ DATA LIST (STP SIGNAL, ST1- VOLTAGE)

    A01DVSPE03

    1. Connect the intelligent tester to the DLC3.

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

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

    4. Check the result.

      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
      E6-14 (ST1-) - E7-7 (E1) Depressed Below 1.5 V
      E6-14 (ST1-) - E7-7 (E1) Released 7.5 to 14 V

    OK

    CHECK FOR INTERMITTENT PROBLEMS

    NG

  3. INSPECT STOP LIGHT SWITCH ASSEMBLY

    A01DXWSE08

    1. Remove the stop light switch.

    2. Measure the resistance of the 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 WIRE HARNESS (STOP LIGHT SWITCH - ECM)

    A01E28IE02

    1. Disconnect the S14 stop light switch connector.

    2. Disconnect the E6 ECM connector.

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

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

    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

    REPLACE ECM