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Home >> Lexus >> 2025 >> NX 350h >> Repair and Diagnosis >> External Pages >> Different car >> Section 68 (Electronically Controlled Brake System - Diagnostic Codes (1 Of 3)) >> ELECTRONICALLY CONTROLLED BRAKE SYSTEM (for Gasoline Model) >> DTC C0040-13: Brake Pedal Switch "A" Circuit Open [11/2021 - ] >> Procedure

DTC C0040-13: Brake Pedal Switch "A" Circuit Open [11/2021 - ]: Procedure

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  1. CHECK DTC 
    1. Check if the same DTC is output.

      Chassis > Brake/EPB > Trouble Codes 

      HINT: 

      When P0571-11, P0571-12, and/or P0571-13 is output together with C0040-13, inspect and repair the trouble areas indicated by P0571-11, P0571-12, and/or P0571-13 first.

      Result

      Result Proceed to
      C0040-13 and P0571-11 are output A
      C0040-13 and P0571-12 are output B
      C0040-13 and P0571-13 are output C
      C0040-13 is output D

    Result: 

    A 

    REPAIR CIRCUITS INDICATED BY OUTPUT DTCS 

    Result: 

    B 

    REPAIR CIRCUITS INDICATED BY OUTPUT DTCS 

    Result: 

    C 

    REPAIR CIRCUITS INDICATED BY OUTPUT DTCS 

    Result: 

    D 

    See step  2

  2. READ VALUE USING GTS (BRAKE PEDAL LOAD SENSING SW) 
    1. Check the value of Data List item Brake Pedal Load Sensing SW when the brake pedal is released.

      Chassis > Brake/EPB > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Brake Pedal Load Sensing SW Brake pedal load sensing switch (brake pedal support assembly) (FSW+ terminal input) OFF / ON OFF: Brake pedal load sensing switch (brake pedal support assembly) OFF HINT: 
      The brake pedal state is determined using the voltage at terminal FSW+

      Chassis > Brake/EPB > Data List 

      Tester Display
      Brake Pedal Load Sensing SW

      Result

      Result Proceed to
      The value of Brake Pedal Load Sensing SW is OFF A
      None of the above conditions are met B

    Result: 

    B 

    See step  6

    Result: 

    A 

    See step  3

  3. READ VALUE USING GTS (BRAKE PEDAL LOAD SENSING SW) 
    1. Check the value of Data List item Brake Pedal Load Sensing SW when the brake pedal is depressed.

      Chassis > Brake/EPB > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Brake Pedal Load Sensing SW Brake pedal load sensing switch (brake pedal support assembly) (FSW+ terminal input) OFF / ON ON: Brake pedal load sensing switch (brake pedal support assembly) ON HINT: 
      The brake pedal state is determined using the voltage at terminal FSW+

      Chassis > Brake/EPB > Data List 

      Tester Display
      Brake Pedal Load Sensing SW

      Result

      Result Proceed to
      The value of Brake Pedal Load Sensing SW is ON A
      None of the above conditions are met B

    Result: 

    B 

    See step  6

    Result: 

    A 

    See step  4

  4. CLEAR DTC 

    Pre-procedure1

    1. None

      Procedure1

    2. Clear the DTCs.

      Chassis > Brake/EPB > Clear DTCs 

      Result

      Proceed to
      NEXT

      Post-procedure1

    3. Turn the ignition switch off.

    Result: 

    NEXT 

    See step  5

  5. RECONFIRM DTC 

    Pre-procedure1

    1. Based on the Freeze Frame Data and interview with the customer, attempt to reproduce the conditions when the malfunction occurred.

      Procedure1

    2. Check if the same DTC is output.

      Chassis > Brake/EPB > Trouble Codes 

      Result

      Result Proceed to
      C0040-13 is not output A
      C0040-13 is output B

      Post-procedure1

    3. None

    Result: 

    A 

    USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2021 - ] 

    Result: 

    B 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [11/2021 - ] 

  6. INSPECT BRAKE PEDAL SUPPORT ASSEMBLY 

    Refer to ON-VEHICLE INSPECTION [11/2021 - ] 

    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 [11/2021 - 03/2022]  , or refer to  REMOVAL [03/2022 - ] 

    Result: 

    OK 

    See step  7

  7. CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY - BRAKE PEDAL SUPPORT ASSEMBLY) 

    Procedure1

    1. Make sure that there is no looseness at the locking part and the connecting part of the connectors.

      OK

      The connector is securely connected.

      Pre-procedure1

    2. Disconnect the A40 brake pedal load sensing switch (brake pedal support assembly) connector.
    3. Disconnect the A36 skid control ECU (brake actuator assembly) connector.

      Procedure2

    4. Check both the connector case and the terminals for deformation and corrosion.

      OK

      No deformation or corrosion.

      Procedure3

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      A36-10 (FSW+) - A40-2 (FSW+) Always Below 1 Ω
      A36-10 (FSW+) or A40-2 (FSW+) - Body ground Always 10 kΩ or higher
      A40-1 (FSW-) - Body ground 1 minute or more after disconnecting the cable from the negative (-) battery terminal Below 1 Ω

      Result

      Proceed to
      OK
      NG

      Post-procedure1

    6. None

    Result: 

    OK 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [11/2021 - ] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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