ECD SYSTEM(for CCo), Diagnostic DTC:P0504

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

DESCRIPTION

The stop light switch assembly is a duplex system that transmits two signals: STP and ST1-. These two signals are used by the ECM to monitor whether or not the brake system is working properly. If the signals, which indicate that the brake pedal is being depressed and released, are detected simultaneously, the ECM interprets this as a malfunction in the stop light switch assembly and stores the DTC.

Tip:

The normal conditions are as shown in the table below.

Signals (ECM Terminal)

Brake Pedal Released

In Transition

Brake Pedal Depressed

STP

OFF

ON

ON

ST1-

ON

ON

OFF

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

P0504

Brake Switch "A" / "B" Correlation

Conditions (a), (b) and (c) continue for 0.5 seconds or more (1 trip detection logic):

(a) Ignition switch ON.

(b) Brake pedal is released.

(c) The STP signal is off when the ST1- signal is off, or the STP signal is on when the ST1- signal is on.

  • Open or short in stop light switch assembly signal circuit

  • Stop light switch assembly

  • ECM

-

DTC stored
Table 1. Related Data List

DTC No.

Data List

P0504

Stop Light Switch

CONFIRMATION DRIVING PATTERN

DTC No.

DTC Detection Drive Pattern

P0504

Release and depress brake pedal with ignition switch ON

WIRING DIAGRAM

A371194E03

CAUTION / NOTICE / HINT

Note:

  • Inspect the fuses of circuits related to this system before performing the following inspection procedure.

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

Tip:

  • Read freeze frame data using the GTS. 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.

  • Stop light switch conditions can be checked using the GTS.

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

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

    5. Check Stop Light Switch when the brake pedal is depressed and released.

Brake Pedal Operation

Specified Condition

Depressed

ON

Released

OFF

PROCEDURE

  1. CHECK TERMINAL VOLTAGE (POWER SOURCE OF STOP LIGHT SWITCH ASSEMBLY)

    E270270C16

    *a

    Front view of wire harness connector

    (to Stop Light Switch Assembly)

    1. 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

      A77-7 (B) - Body ground

      Always

      11 to 14 V

    Result

    Proceed to

    OK

    NG
    NG

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

    OK

  2. CHECK TERMINAL VOLTAGE (POWER SOURCE OF STOP LIGHT SWITCH ASSEMBLY)

    E270270C17

    *a

    Front view of wire harness connector

    (to Stop Light Switch Assembly)

    1. Disconnect the stop light switch assembly connector.

    2. Turn the ignition switch to ON.

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      A77-6 (B) - Body ground

      Engine switch on (IG)

      11 to 14 V

    Result

    Proceed to

    OK

    NG
    NG

    CHECK HARNESS AND CONNECTOR (IG2 RELAY - STOP LIGHT SWITCH ASSEMBLY)Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BODY GROUND)

    1. Disconnect the stop light switch assembly connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      A77-2 (GND) - Body ground

      Always

      Below 1 Ω

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK TERMINAL VOLTAGE (STP AND ST1- VOLTAGE)

    1. A275087C02

      *a

      Brake Pedal Depressed

      *b

      Brake Pedal Released

      *c

      Front view of wire harness connector

      (to ECM)

      Disconnect the ECM connector.

    2. Turn the ignition switch to ON.

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

      Standard Voltage

      Tester Connection

      Brake Pedal Condition

      Switch Condition

      A61-34 (ST1-) - Body ground

      Released

      7.5 to 14 V

      Depressed

      Below 1.5 V

      A61-35 (STP) - Body ground

      Released

      Below 1.5 V

      Depressed

      7.5 to 14 V

    Result

    Proceed to

    OK

    NG
    OK

    REPLACE ECM

    Click here

    NG

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

    1. Disconnect the stop light switch assembly connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      A77-5 (L) - A61-34 (ST1-)

      Always

      Below 1 Ω

      A77-3 (L) - A61-35 (STP)

      Always

      Below 1 Ω

      A77-5 (L) or A61-34 (ST1-) - Body ground

      Always

      10 kΩ or higher

      A77-3 (L) or A61-35 (STP) - Body ground

      Always

      10 kΩ or higher

    Result

    Proceed to

    OK

    NG
    OK

    REPLACE STOP LAMP SWITCH ASSEMBLY

    Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  6. CHECK HARNESS AND CONNECTOR (IG2 RELAY - STOP LIGHT SWITCH ASSEMBLY)

    1. Remove the IG2 relay from the engine room relay block and junction block assembly.

    2. Disconnect the stop light switch assembly connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      IG2 relay terminal 5 - A77-6 (B)

      Always

      Below 1 Ω

      IG2 relay terminal 5 or A77-6 (B) - Body ground

      Always

      10 kΩ or higher

    Result

    Proceed to

    OK

    NG
    OK

    GO TO ECM POWER SOURCE CIRCUIT

    Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR