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 of depressing and releasing the brake pedal 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

A01CIW0E01

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. Replace the normal DLC3 cable (12 V specification) for the intelligent tester with the 24 V DLC3 cable.

      Note

      Be sure to use the 24 V DLC3 cable when connecting the intelligent tester to the DLC3. Using the normal DLC3 cable (12 V specification) will cause damage to the tester.

    2. Connect the intelligent tester to the DLC3.

    3. Turn the ignition switch to the ON position.

    4. Turn the tester on.

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

    6. 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. A01CI2LE02

      Disconnect the stop light switch connector.

    2. Turn the ignition switch to the ON position.

    3. Measure the voltage between the terminals 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
      S15-2 - Body ground Ignition switch in the ON position 18 to 27 V

    4. Reconnect the stop light switch connector.


    NG

    INSPECT FUSE (STOP FUSE) Click here

    OK

  2. INSPECT STOP LIGHT SWITCH ASSEMBLY


    1. A01CGZHE05

      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 Below 1 Ω
      Switch pin pushed 10 kΩ or higher

    3. Reinstall the stop light switch assembly.


    NG

    REPLACE STOP LIGHT SWITCH ASSEMBLY

    OK

  3. 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

  4. INSPECT FUSE (STOP FUSE)


    1. A01CHAOE01

      Remove the STOP 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 STOP fuse.


    NG

    REPLACE FUSE (STOP FUSE)

    OK

  5. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH - BATTERY)


    1. A01CI2LE02

      Disconnect the negative battery terminal.

    2. Disconnect the positive battery terminal.

    3. Disconnect the stop light switch connector.

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

      Standard resistance
      Check for open
      Tester Connection Condition Specified Condition
      Positive battery terminal - S15-2 Always Below 1 Ω
      Check for short
      Tester Connection Condition Specified Condition
      Positive battery terminal or S15-2 - Body ground Always 10 kΩ or higher

    5. Reconnect the stop light switch connector.

    6. Reconnect the positive battery terminal.

    7. Reconnect the negative battery terminal.


    NG

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

    OK

  6. INSPECT FUSE (ECU-IG FUSE)


    1. A01CH23E01

      Remove the ECU-IG 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 ECU-IG fuse.


    NG

    REPLACE FUSE (ECU-IG FUSE)

    OK

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