ECD SYSTEM, Diagnostic DTC:P0504

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

DESCRIPTION

In this system, signals of the stop light switch are used to judge whether the brake system is abnormal or not.

The stop light switch has a duplex system (signals STP and ST1-) to memorize the abnormality when the signals indicating that the brake pedal is depressed and released are detected simultaneously.

Tech Tips

Normal condition is as 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) and (b) continue for 0.5 seconds or more:

(a) Ignition switch in the ON position

(b) Open or short in stop light switch signal circuit

  • Short in stop light switch signal circuit

  • Stop light switch

  • ECM

WIRING DIAGRAM

A01CGNTE01

INSPECTION PROCEDURE

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 be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

  • STP signal conditions can be checked using the intelligent tester.


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to the ON position.

    3. Turn the tester on.

    4. Enter the following menu items: Powertrain / Engine and ECT / Data List / Stop Light Switch.

    5. Check the STP signal when the brake pedal is depressed and released.

      Result
      Brake Pedal Operation Specified Condition
      Depressed STP signal ON
      Released STP signal OFF

PROCEDURE


  1. CHECK STOP LIGHT SWITCH ASSEMBLY (TERMINAL VOLTAGE)


    1. A01CI2LE05

      Disconnect the stop light switch connector.

    2. Turn the ignition switch to the ON position.

    3. Measure the voltage according to the value(s) in the table below.

      Standard voltage
      Tester Connection Condition Specified Condition
      S15-4 - Body ground Ignition switch in the ON position 18 to 27 V

    4. Reconnect the stop light switch connector.


    NG

    CHECK ECM (STP AND ST1- VOLTAGE) Click here

    OK

  2. CHECK STOP LIGHT SWITCH ASSEMBLY (TERMINAL VOLTAGE)


    1. A01CI2LE05

      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
      S15-2 - Body ground Always 18 to 27 V

    3. Reconnect the stop light switch assembly connector.


    NG

    INSPECT FUSE (GAUGE FUSE) Click here

    OK

  3. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. A01CJ4ME03

      Remove the stop light switch assembly.

    2. Measure the resistance according to the value(s) in the table below.

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

    3. Reinstall the stop light switch assembly.


    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY

    OK

  4. CHECK ECM (STP AND ST1- VOLTAGE)


    1. A01CH6GE01

      Disconnect the ECM connector.

    2. Turn the ignition switch to the ON position.

    3. Measure the voltage according to the value(s) in the table below.

      Standard voltage
      Tester Connection Condition Specified Condition
      E25-8 (ST1-) - Body ground Depressed Below 2 V
      Released 18 to 27 V
      E25-18 (STP) - Body ground Depressed 18 to 27 V
      Released Below 2 V

    4. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH - ECM)

    OK

    REPLACE ECM

  5. INSPECT FUSE (GAUGE FUSE)


    1. Remove the GAUGE fuse from the No. 1 relay block.

    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      1 - 2 Always Below 1 Ω

    3. Reinstall the GAUGE fuse.


    NG

    REPLACE FUSE (GAUGE FUSE)

    OK

  6. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - IGNITION SWITCH ASSEMBLY)


    1. A01CIG3E02

      Disconnect the stop light switch assembly connector.

    2. Disconnect the ignition switch assembly connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Check for open
      Tester Connection Condition Specified Condition
      S15-4 - I6-10 Always Below 1 Ω

    4. Reconnect the stop light switch assembly connector.

    5. Reconnect the ignition switch assembly connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - IGNITION SWITCH ASSEMBLY)

    OK

  7. INSPECT IGNITION SWITCH ASSEMBLY


    1. A01CHNME07

      Disconnect the ignition switch assembly connector.

    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      All terminal LOCK 10 kΩ or higher
      I6-9 (AM1) - I6-10 (IG1) ON Below 1 Ω

    3. Reconnect the ignition switch assembly connector.


    NG

    REPLACE IGNITION SWITCH ASSEMBLY

    OK

  8. INSPECT FUSE (AM1 FUSE)


    1. A01CGXAE01

      Remove the AM1 fuse from the No. 2 relay block.

    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      1 - 2 Always Below 1 Ω

    3. Reinstall the AM1 fuse.


    NG

    REPLACE FUSE (AM1 FUSE)

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (IGNITION SWITCH ASSEMBLY - BATTERY)

  9. INSPECT FUSE (STOP FUSE)


    1. A01CIX3E01

      Remove the STOP fuse from the No. 1 relay block.

    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      1 - 2 Always Below 1 Ω

    3. Reinstall the STOP fuse.


    NG

    REPLACE FUSE (STOP FUSE)

    OK

  10. INSPECT FUSE (HEAD FUSE)


    1. A01CJAYE01

      Remove the HEAD fuse from the No. 2 relay block.

    2. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Tester Connection Condition Specified Condition
      1 - 2 Always Below 1 Ω

    3. Reconnect the HEAD fuse.


    NG

    REPLACE FUSE (HEAD FUSE)

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BATTERY)