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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) >> Downhill Assist Control Indicator Light Circuit [03/2024 - ] >> Procedure

Downhill Assist Control Indicator Light Circuit [03/2024 - ]: Procedure

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  1. READ VALUE USING GTS (DOWNHILL ASSIST CONTROL SW) 
    1. Check the downhill assist control indicator light and mode condition on the GTS changes according to downhill assist control switch (electric parking brake switch assembly) operation.

      Chassis > Brake/EPB > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Downhill Assist Control SW Downhill assist control switch (electric parking brake switch assembly) OFF / ON OFF: Downhill assist control switch (electric parking brake switch assembly) OFF
      ON: Downhill assist control switch (electric parking brake switch assembly) ON      		 for AWD

      Chassis > Brake/EPB > Data List 

      Tester Display
      Downhill Assist Control SW

      Standard

      Downhill Assist Control Switch (Electric Parking Brake Switch Assembly) Operation Mode Condition Display Downhill Assist Control Indicator Light
      Not pressed OFF Does not come on
      Pressing the downhill assist control switch (electric parking brake switch assembly) ON Comes 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: 

    B 

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

    Result: 

    C 

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

    Result: 

    A 

    See step  2

  2. INSPECT ELECTRIC PARKING BRAKE SWITCH ASSEMBLY 

    Refer to INSPECTION [03/2024 - ]

    OK

    The downhill assist control switch (electric parking brake switch assembly) is normal.

    Result

    Result
    OK
    NG

    Result: 

    NG 

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

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (BRAKE ACTUATOR ASSEMBLY - ELECTRIC PARKING BRAKE SWITCH ASSEMBLY) 
    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.

    2. Disconnect the A36 skid control ECU (brake actuator assembly) connector.
    3. Disconnect the D161 downhill assist control switch (electric parking brake switch assembly) connector.
    4. Check both the connector case and the terminals 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
      A36-8 (TRS) - D161-13 (B) Always Below 1 Ω
      A36-8 (TRS) or D161-13 (B) - 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

      Result
      OK
      NG

    Result: 

    OK 

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

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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