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Home >> Lexus >> 2018 >> 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 C1429: Open or Short in Brake Pedal Load Sensing Switch [12/2017 - 09/2018] >> Procedure

DTC C1429: Open or Short in Brake Pedal Load Sensing Switch [12/2017 - 09/2018]: Procedure

  1. READ VALUE USING TECHSTREAM (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
      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
      Brake Pedal Load Sensing SW
    4. Check that the brake pedal load sensing switch display observed on the Techstream changes according to brake pedal operation.

      OK

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

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  3

    Result: 

    OK 

    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
      DTC C1429 is not output. A
      DTC C1429 is 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