ECD SYSTEM, Diagnostic DTC:P0504

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

DESCRIPTION

The stop light switch 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 and stores the DTC.

Tech Tips

The normal signal conditions are as shown in the table below.

Signal (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 to 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 signal circuit

  • STOP fuse

  • IGN fuse

  • Stop light switch

  • ECM

 - DTC stored
Related Data List
DTC No. Data List
P0504 Stop Light Switch

CONFIRMATION DRIVING PATTERN

P0504
DTC Detection Drive Pattern Depress and release brake pedal with ignition switch to ON

WIRING DIAGRAM

B003RSXE04

CAUTION / NOTICE / HINT

Tech Tips

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.

Note


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

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

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (TERMINAL VOLTAGE)


    1. B003N0DC09
      *a

      Front view of wire harness connector

      (to Stop Light Switch Assembly)

      Disconnect the stop light switch assembly connector.

    2. Turn the igntion switch to ON

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A64-6 (B) - Body ground Ignition switch ON 11 to 14 V
      A64-7 (B) - Body ground Always 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - BATTERY,INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

    OK

  2. 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 thetable below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A64-2 (GND) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK ECM (STP AND ST1- VOLTAGE)


    1. B003NYMC16
      *a Brake Pedal Depressed
      *b Brake Pedal Released
      *c

      Component with harness connected

      (ECM)

      Turn the ignition switch to ON

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

      Standard Voltage
      Tester Connection Brake Pedal Condition Specified Condition
      G140-14 (ST1-) - Body ground Released 7.5 to 14 V
      Depressed 0 to 1.5 V
      G140-15 (STP) - Body ground Released 0 to 1.5 V
      Depressed 7.5 to 14 V
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

  4. 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
      A64-3 (L) - G140-15 (STP) Always Below 1 Ω
      A64-5 (L) - G140-14 (ST1-) Always Below 1 Ω
      A64-3 (L) or G140-15 (STP) - Body ground and other terminals Always 10 kΩ or higher
      A64-5 (L) or G140-14 (ST1-) - Body ground and other terminals Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR