SFI SYSTEM, 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 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 this 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

  • [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. Detection Item DTC Detection Condition Trouble Area MIL Memory
P0504 Brake Switch "A" / "B" Correlation

Conditions (a) and (b) are met for 0.5 seconds or more (1 trip detection logic):

(a) Ignition switch ON

(b) STP signal off when ST1- signal off

  • Open or short in stop light switch signal circuit

  • Wire harness or connector

  • Stop light switch assembly

  • No. 1 integration relay

  • ECM

 Does not come on DTC stored

WIRING DIAGRAM

A00492LE01
A004B71E01

CAUTION / NOTICE / HINT

Note

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

Tech Tips


  • Stop light switch assembly 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 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

  • Read freeze frame data using the GTS. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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.

PROCEDURE


  1. READ VALUE USING GTS (ST1 AND STOP LIGHT SWITCH)


    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 / ST1 and Stop Light Switch.

    5. Read the value displayed on the GTS.

      OK
      Brake Pedal Operation Stop Light Switch ST1
      Depressed ON ON
      Released OFF OFF
      Result
      Proceed to
      OK
      NG

    OK

    CHECK FOR INTERMITTENT PROBLEMS Click here

    NG

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

    A004BKMC01
    *A for LED Type Stop Light *B for Bulb Type Stop Light
    *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
      for LED Type Stop Light
      Tester Connection Condition Specified Condition
      A83-7 (B) - Body ground Always 11 to 14 V
      for Bulb Type Stop Light
      Tester Connection Condition Specified Condition
      A89-2 (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

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

    A004BKMC02
    *A for LED Type Stop Light *B for Bulb Type Stop Light
    *C

    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
      for LED Type Stop Light
      Tester Connection Switch Condition Specified Condition
      A83-6 (B) - Body ground Ignition switch ON 11 to 14 V
      for Bulb Type Stop Light
      Tester Connection Switch Condition Specified Condition
      A89-4 (B) - Body ground Ignition switch ON 11 to 14 V
      Result
      Result Proceed to
      OK*1 A
      OK*2 B
      NG C

      • *1: for LED Type Stop Light

      • *2: for Bulb Type Stop Light


    B

    CHECK TERMINAL VOLTAGE (STP AND ST1- VOLTAGE) Click here

    C

    CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - NO. 1 INTEGRATION RELAY) Click here

    A

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


    1. Disconnect the A83 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
      A83-2(GND) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Disconnect the ECM connector.

      A0048KGC15
      *a Brake Pedal Depressed *b Brake Pedal Released
      *c

      Front view of wire harness connector

      (to ECM)

      		 - -

    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 Operation Specified Condition
      A58-10 (ST1-) - Body ground Released 7.5 to 14 V
      Depressed Below 1.5 V
      A58-9 (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

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


    1. Disconnect the A83 stop light switch assembly connector.*1

    2. Disconnect the A89 stop light switch assembly connector.*2

    3. Disconnect the A58 ECM connector.

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

      *1: for LED Type Stop Light

      *2: for Bulb Type Stop Light

      Standard Resistance
      for LED Type Stop Light
      Tester Connection Condition Specified Condition
      A83-5 (L) - A58-10 (ST1-) Always Below 1 Ω
      A83-3 (L) - A58-9 (STP) Always Below 1 Ω
      A83-5 (L) or A58-10 (ST1-) - Body ground and other terminals Always 10 kΩ or higher
      A83-3 (L) or A58-9 (STP) - Body ground and other terminals Always 10 kΩ or higher
      for Bulb Type Stop Light
      Tester Connection Condition Specified Condition
      A89-3 (L) - A58-10 (ST1-) Always Below 1 Ω
      A89-1 (L) - A58-9 (STP) Always Below 1 Ω
      A89-3 (L) or A58-10 (ST1-) - Body ground and other terminals Always 10 kΩ or higher
      A89-1 (L) or A58-9 (STP) - 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

  7. CHECK HARNESS AND CONNECTOR (STOP LIGHT SWITCH ASSEMBLY - NO. 1 INTEGRATION RELAY)


    1. Disconnect the A83 stop light switch assembly connector.*1

    2. Disconnect the A89 stop light switch assembly connector.*2

    3. Disconnect the No. 1 integration relay connector.

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

      *1: for LED Type Stop Light

      *2: for Bulb Type Stop Light

      Standard Resistance
      for LED Type Stop Light
      Tester Connection Condition Specified Condition
      A83-6 (B) - 1D-19 Always Below 1 Ω
      A83-6 (B) or 1D-19 - Body ground and other terminals Always 10 kΩ or higher
      for Bulb Type Stop Light
      Tester Connection Condition Specified Condition
      A89-4 (B) - 1D-19 Always Below 1 Ω
      A89-4 (B) or 1D-19 - Body ground and other terminals Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE NO. 1 INTEGRATION RELAY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR