SFI 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 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 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

  • [OFF] denotes ground potential.

  • [ON] denotes battery potential (+B).

  • On the GTS, both the Data List items Stop Light Switch and ST1 are ON when the brake pedal is depressed because the ST1 indication characteristic is opposite to the Stop Light Switch indication.

DTC No. DTC Detection Condition Trouble Area
P0504

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

(a) The engine switch is on (IG).

(b) The STP signal is OFF when the ST1- signal is OFF.

  • Short in stop light switch signal circuit

  • Stop light switch

  • ECM

WIRING DIAGRAM

A01X59NE02

CAUTION / NOTICE / HINT

Note

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

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, if the air-fuel ratio was lean or rich, 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 engine switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Stop Light Switch and ST1.

    5. Check the Data List indication when the brake pedal is depressed and released.

Brake Pedal Operation Stop Light Switch ST1
Depressed ON ON
Released OFF OFF

PROCEDURE


  1. READ VALUE USING GTS (STOP LIGHT SWITCH)


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

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

    5. Read the value displayed on the GTS.

      OK
      Tester Display Measurement Item/Range (display) Normal Condition
      Stop Light Switch Stop light switch status: ON or OFF

      ON: Brake pedal depressed

      OFF: Brake pedal released

    OK

    CHECK FOR INTERMITTENT PROBLEMS Click here

    NG

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

    A01X8NHE01
    *1 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 Switch Condition Specified Condition
      A73-1 (B) - Body ground Always 11 to 14 V

    NG

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

    OK

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

    A01XB7VE01
    *1 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 Switch Condition Specified Condition
      A73-5 (B) - Body ground Engine switch on (IG) 11 to 14 V

    NG

    CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - NO. 2 INTEGRATION RELAY) Click here

    OK

  4. 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 Switch Condition Specified Condition
      A73-3 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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

    A01X478E02

    1. Disconnect the ECM connector.

    2. Turn the engine switch on (IG).

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

      Standard Voltage (for RHD)
      Tester Connection Brake Pedal Operation Specified Condition
      A52-35 (ST1-) - Body ground Released 7.5 to 14 V
      Depressed Below 1.5 V
      A52-36 (STP) - Body ground Released Below 1.5 V
      Depressed 7.5 to 14 V
      Standard Voltage (for LHD)
      Tester Connection Brake Pedal Operation Specified Condition
      A38-35 (ST1-) - Body ground Released 7.5 to 14 V
      Depressed Below 1.5 V
      A38-36 (STP) - Body ground Released Below 1.5 V
      Depressed 7.5 to 14 V

    OK

    REPLACE ECM Click here

    NG

  6. 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 (for RHD)
      Tester Connection Brake Pedal Operation Specified Condition
      A73-4 (L) - A52-35 (ST1-) Always Below 1 Ω
      A73-2 (L) - A52-36 (STP) Always Below 1 Ω
      A73-4 (L) or A52-35 (ST1-) - Body ground Always 10 kΩ or higher
      A73-2 (L) or A52-36 (STP) - Body ground Always 10 kΩ or higher
      Standard Resistance (for LHD)
      Tester Connection Brake Pedal Operation Specified Condition
      A73-4 (L) - A38-35 (ST1-) Always Below 1 Ω
      A73-2 (L) - A38-36 (STP) Always Below 1 Ω
      A73-4 (L) or A38-35 (ST1-) - Body ground Always 10 kΩ or higher
      A73-2 (L) or A38-36 (STP) - Body ground Always 10 kΩ or higher

    OK

    REPLACE STOP LIGHT SWITCH ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  7. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - NO. 2 INTEGRATION RELAY)


    1. Disconnect the stop light switch assembly connector.

    2. Disconnect the No. 2 integration relay connector.

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

      Standard Resistance
      Tester Connection Brake Pedal Operation Specified Condition
      A73-5 (B) - 1R-1 Always Below 1 Ω
      A73-5 (B) or 1R-1 - Body ground Always 10 kΩ or higher

    OK

    REPLACE NO. 2 INTEGRATION RELAY

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR