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Home >> Lexus >> 2025 >> NX 350h >> Repair and Diagnosis >> External Pages >> Different car >> Section 96 (Electronically Controlled Brake System - Diagnostic Codes (3 Of 3), Symptom Tests & Circuit Tests) >> ELECTRONICALLY CONTROLLED BRAKE SYSTEM (for Gasoline Model) >> Brake Hold Standby Indicator Light Circuit [03/2024 - ] >> Procedure

Brake Hold Standby Indicator Light Circuit [03/2024 - ]: Procedure

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  1. PRE-CHECK 
    1. If the brake hold standby indicator light does not illuminate even though the brake hold switch (electric parking brake switch assembly) is pushed, check that the brake hold function operation conditions are met.
      1. The driver door is closed.
      2. The driver seat belt is fastened.
      3. The system is normal.

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  2

  2. READ VALUE USING GTS (BRAKE HOLD READY) 
    1. All of the following brake hold operation conditions are met:
      1. The driver door is closed.
      2. The driver seat belt is fastened.
    2. Check the brake hold standby indicator light and mode condition on the GTS changes according to brake hold switch (electric parking brake switch assembly) operation.

      Chassis > Brake/EPB > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Brake Hold Ready Brake hold control permission status Not in stand-by mode / Stand-by mode Not in stand-by mode: Brake hold function not operating (brake hold standby indicator not illuminated)
      Stand-by mode: Brake hold function stand-by state (brake hold standby indicator illuminated)
      -

      Chassis > Brake/EPB > Data List 

      Tester Display
      Brake Hold Ready

      Standard

      Brake Hold Switch (Electric Parking Brake Switch Assembly) Operation Mode Condition Display Brake Hold Standby Indicator Light
      Not pressed Not in stand-by mode Does not come on
      Pressing the brake hold switch (electric parking brake switch assembly) Stand-by mode come on

      Result

      Result Proceed to
      Indicator light and mode condition display do not change A
      Mode condition display is normal, but indicator light does not change B
      Indicator light and mode condition display are normal C

    Result: 

    INSPECT METER / GAUGE SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2021 - ] 

    Result: 

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

    Result: 

    See step  3

  3. INSPECT ELECTRIC PARKING BRAKE SWITCH ASSEMBLY 

    Refer to INSPECTION [03/2024 - ]

    OK

    The brake hold switch (electric parking brake switch assembly) is normal.

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE ELECTRIC PARKING BRAKE SWITCH ASSEMBLY. Refer to  REMOVAL [11/2021 - ] 

    Result: 

    OK 

    See step  4

  4. CHECK HARNESS AND CONNECTOR (ELECTRIC PARKING BRAKE SWITCH ASSEMBLY - BRAKE ACTUATOR ASSEMBLY) 
    1. Make sure that there is no looseness at the locking part and the connecting part of the connector.

      OK

      The connector is securely connected.

    2. Disconnect the A36 skid control ECU (brake actuator assembly) connector.
    3. Disconnect the D161 brake hold switch (electric parking brake switch assembly) connector.
    4. Check both the connector case and the terminal for deformation and corrosion.

      OK

      No deformation or corrosion.

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

      Standard Resistance

      Tester Connection Condition Specified Condition
      D161-3 (+B) - A36-42 (HZRI) Always Below 1 Ω
      D161-3 (+B) or A36-42 (HZRI) - Body ground Always 10 kΩ or higher
      D161-7 (E) - Body ground 1 minute or more after disconnecting the cable from the negative (-) battery terminal Below 1 Ω

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

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

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR