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Home › Lexus › 2008 › SC 430 › Repair and Diagnosis › Engine Performance › Engine Control System › SFI System › DTC P0504: Brake Switch "A" / "B" Correlation › Inspection Procedure

Inspection Procedure

  1. CHECK STOP LIGHT SWITCH 
    1. Check that the stop lights turn on and off normally when the brake pedal is depressed and released.

      NG: REPAIR OR REPLACE STOP LIGHT SWITCH 

      OK: Go to next step 

  2. INSPECT STOP LIGHT SWITCH 
    1. Disconnect the S10 stop light switch.
    2. Measure the resistance of the switch.

    Standard resistance 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Switch Condition Specified Condition
    1-2 Switch pin not pushed Below 1 Ω
    3-4 Switch pin not pushed 10 kΩ or higher
    1-2 Switch pin pushed in 10 kΩ or higher
    3-4 Switch pin pushed in Below 1 Ω

    NG: REPLACE STOP LIGHT SWITCH 

    Fig 1: Inspecting Stop Light Switch
    G05291459Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to next step 

  3. READ VALUE OF TECHSTREAM (STOP LIGHT SWITCH) 
    1. Connect the Techstream to the DLC3.
    2. Turn the ignition switch ON.
    3. Enter the following menus: Powertrain / Engine and ECT / Data List / Stop Light Switch.
    4. Confirm the stop light switch status when the brake pedal is depressed and released.

      OK 

      BRAKE PEDAL CONDITION CHART

      Brake Pedal Condition Specified Condition
      Depressed STP Signal ON
      Released STP Signal OFF
    5. Measure the voltage of the ECM when the brake pedal is depressed and released.

    Standard voltage 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Brake Pedal Condition Specified Condition
    E6-8 (ST1-) - E3-7 (E1) Depressed Below 1.5 V
    E6-8 (ST1-) - E3-7 (E1) Released 7.5 to 14 V

    OK: CHECK FOR INTERMITTENT PROBLEMS 

    Fig 2: Identifying Brake Pedal Depressed And Released Position
    G05291460Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: Go to next step 

  4. CHECK WIRE HARNESS (STOP LIGHT SWITCH - ECM) 
    1. Disconnect the S10 stop light switch connector.
    2. Disconnect the E5 and E6 ECM connectors.
    3. Measure the resistance of the wire harness side connectors.

    Standard resistance 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Specified Condition
    S10-1 - E5-4 (STP) Below 1 Ω
    S10-4 - E6-8 (ST1-) Below 1 Ω
    S10-1 or E5-4 (STP) - Body ground 10 kΩ or higher
    S10-4 or E6-8 (ST1-) - Body ground 10 kΩ or higher

    NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 

    Fig 3: Checking Wire Harness (Stop Light Switch - ECM)
    G05291461Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: REPLACE ECM 

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