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Home >> Lexus >> 2021 >> LS 500 Base, AWD >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> Electronically Controlled Brake System (W/ Vacuum Brake Booster) - Diagnostic Codes (3 Of 4) >> ELECTRONICALLY CONTROLLED BRAKE SYSTEM (w/ Vacuum Brake Booster) >> DTC C1430: Brake Pedal Load Sensing Switch OFF Stuck Malfunction; DTC C1431: Brake Pedal Load Sensing Switch ON Stuck Malfunction [12/2017 - 09/2018] >> Procedure

DTC C1430: Brake Pedal Load Sensing Switch OFF Stuck Malfunction; DTC C1431: Brake Pedal Load Sensing Switch ON Stuck Malfunction [12/2017 - 09/2018]: Procedure

  1. READ VALUE USING TECHSTREAM (STOP LIGHT SW AND BRAKE PEDAL LOAD SENSING SW) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Select the Data List using the Techstream.

      Refer to DATA LIST / ACTIVE TEST [12/2017 - 09/2018]

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Stop Light SW Stop light switch assembly ON or OFF ON: Brake pedal depressed
      OFF: Brake pedal released
      -
      Brake Pedal Load Sensing SW Brake pedal load sensing switch ON or OFF ON: Brake pedal depressed beyond a specified point
      OFF: Brake pedal not depressed beyond a specified point
      -

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display
      Stop Light SW
      Brake Pedal Load Sensing SW
    4. Check that the stop light switch display and brake pedal load sensing switch display observed on the Techstream change according to brake pedal operation.

      OK

      The Techstream displays ON or OFF according to brake pedal operation.

    5. Slowly depress the brake pedal, and check when the stop light switch assembly and brake pedal load sensing switch turn on.

      OK

      First the stop light switch assembly should turn on, and then the brake pedal load sensing switch should turn on.

      Result

      Result Proceed to
      OK A
      NG (Turning on of the brake pedal load sensing switch is not confirmed.) B
      NG (The brake pedal load sensing switch turns on first.) C

    Result: 

    B 

    See step  3

    Result: 

    C 

    See step  5

    Result: 

    A 

    See step  2

  2. RECONFIRM DTC 
    1. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [12/2017 - 09/2018]

      Chassis > ABS/VSC/TRAC > Clear DTCs 

    2. Turn the engine switch off.
    3. Start the engine.
    4. Perform a road test.
    5. Check if the same DTC is output.

      Refer to DTC CHECK / CLEAR [12/2017 - 09/2018]

      Chassis > ABS/VSC/TRAC > Trouble Codes 

      Result

      Result Proceed to
      DTCs C1430 and C1431 are not output. A
      DTCs C1430 and/or C1431 are output. B

    Result: 

    A 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [12/2017 - 09/2018] 

    Result: 

    B 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [12/2017 - 09/2018] 

  3. INSPECT BRAKE PEDAL SUPPORT ASSEMBLY 
    1. Inspect the brake pedal load sensing switch (brake pedal support assembly).

      Refer to ON-VEHICLE INSPECTION [12/2017 - 10/2023]

      OK

      The brake pedal load sensing switch (brake pedal support assembly) is normal.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE BRAKE PEDAL SUPPORT ASSEMBLY. Refer to  REMOVAL [12/2017 - 09/2018] 

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY - BRAKE PEDAL SUPPORT ASSEMBLY) 
    1. Make sure that there is no looseness at the locking part and the connecting part of the connector.
    2. Disconnect the A9 skid control ECU (brake actuator assembly) connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A9-23 (FSW+) - A5-2 (FSW+) Always Below 1 Ω
      A9-23 (FSW+) or A5-2 (FSW+) - Body ground Always 10 kΩ or higher
      A5-1 (FSW-) - Body ground Always Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [12/2017 - 09/2018] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  5. CHECK BRAKE PEDAL HEIGHT AND STOP LIGHT SWITCH ASSEMBLY INSTALLATION 
    1. Turn the engine switch off.
    2. Check the brake pedal height and stop light switch assembly installation.

      Refer to INSTALLATION [12/2017 - 10/2023]

      OK

      The brake pedal height and stop light switch assembly installation are normal.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE BRAKE PEDAL SUPPORT ASSEMBLY. Refer to  REMOVAL [12/2017 - 09/2018] 

    Result: 

    NG 

    ADJUST BRAKE PEDAL HEIGHT OR STOP LIGHT SWITCH ASSEMBLY INSTALLATION. Refer to  ADJUSTMENT [12/2017 - 10/2020]