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

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

DESCRIPTION

In this system, 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 assembly.

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


  • (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 assembly

  • ECM

WIRING DIAGRAM

A01KGBPE01

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. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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.

PROCEDURE


  1. CHECK STOP LIGHT CIRCUIT


    1. Check if the stop light turns on and off when the brake pedal is depressed and released.

      OK
      Stop light turns on and off normally

    NG

    REPAIR OR REPLACE STOP LIGHT SWITCH CIRCUIT

    OK

  2. READ VALUE USING INTELLIGENT TESTER (STP SIGNAL, ST1- VOLTAGE)


    1. A01KGCQE24
      Text in Illustration
      *1 ECM Connector
      *a Brake Pedal Depressed
      *b Brake Pedal Released

      Connect the intelligent tester to the DLC3.

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

    3. Select the following menus: Powertrain / Engine and ECT / Data List / Stop Light SW.

    4. Check the result.

      OK
      Brake Pedal Specified Condition
      Depressed STP signal on
      Released STP signal off

    5. Measure the voltage of the E12 and E17 ECM connectors.

      Standard voltage
      Tester Connection Brake Pedal Specified Condition
      E17-9 (ST1-) - E12-14 (E2) Depressed Below 1.5 V
      Released 7.5 to 14 V

    OK

    CHECK FOR INTERMITTENT PROBLEMS Click here

    NG

  3. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. A01KG6EE03
      Text in Illustration
      *a Free
      *b Pushed in

      Remove the stop light switch assembly.

    2. Check the resistance.

      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 ASSEMBLY - ECM)


    1. Disconnect the S8 stop light switch assembly connector.

    2. Disconnect the E17 ECM connector.

    3. Check the resistance.

      Standard resistance (Check for open)
      Tester Connections Specified Conditions
      S8-1 - E17-8 (STP) Below 1 Ω
      S8-3 - E17-9 (ST1-) Below 1 Ω
      Standard resistance (Check for short)
      Tester Connections Specified Conditions
      S8-1 or E17-8 (STP) - Body ground 10 kΩ or higher
      S8-3 or E17-9 (ST1-) - Body ground 10 kΩ or higher

    4. Reconnect the stop light switch assembly connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM Click here