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Home >> Lexus >> 2021 >> LS 500h RWD >> Repair and Diagnosis >> Brakes >> Parking Brake System >> Electric Parking Brake System (W/O Advanced Park) - Diagnostic Codes & Symptom Tests >> ELECTRIC PARKING BRAKE SYSTEM (w/o Advanced Park) >> Electric Parking Brake does not Operate [10/2020 - 10/2023] >> Procedure

Electric Parking Brake does not Operate [10/2020 - 10/2023]: Procedure

  1. VEHICLE OPERATION CHECK 
    1. Turn the power switch on (READY) and change the shift state to D. Then depress the brake pedal and push the electric parking brake switch assembly to the lock side for 1 second. Check the parking brake indicator light (red) condition.
    2. Release the brake pedal and check that the vehicle does not move.
    3. Depress the brake pedal and pull the electric parking brake switch assembly to the release side for 1 second. Check the parking brake indicator light (red) condition.
    4. Release the brake pedal and check that the vehicle moves.

      Result

      Result Proceed to
      Lock and release control is normal; parking brake indicator light (red) is off or is blinking A
      Lock and release control is malfunctioning; parking brake indicator light (red) is illuminated or off depending on switch operation B
      Lock and release control is malfunctioning; parking brake indicator light (red) is off or is blinking C

    Result: 

    B 

    See step  4

    Result: 

    C 

    See step  5

    Result: 

    A 

    See step  2

  2. PERFORM TECHSTREAM (PKB LIGHT) 
    1. Turn the power switch off.
    2. Connect the Techstream to the DLC3.
    3. Turn the power switch on (IG) and the Techstream on.
    4. Enter the following menus: Chassis / Electric Parking Brake / Active Test.
    5. Check the condition of the parking brake indicator light (red) by operating the Techstream.

      Chassis > Electric Parking Brake > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      PKB Light Parking brake indicator light (red) ON or OFF
      • Vehicle stopped
      • Power switch on (IG)
      • Parking brake released

      Chassis > Electric Parking Brake > Active Test 

      Tester Display
      PKB Light

      OK

      Indicator light turns on when operating the Techstream.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE PARKING BRAKE ECU ASSEMBLY. Refer to  REMOVAL [10/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

    Result: 

    NG 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (PARKING BRAKE ECU ASSEMBLY - COMBINATION METER ASSEMBLY) 
    1. Turn the power switch off.
    2. Disconnect the L76 parking brake ECU assembly connector.
    3. Disconnect the G34 combination meter assembly connector.
    4. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      L76-7 (TX) - G34-5 (EPB)* Always Below 1 Ω
      L76-7 (TX) or G34-5 (EPB)* - Body ground Always 10 kΩ or higher

      HINT: 

      *: EPB stands for electric parking brake

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    GO TO METER / GAUGE SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [10/2020 - 11/2021]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2021 - 10/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

  4. READ VALUE USING TECHSTREAM (TENSION1 VOLTAGE, TENSION2 VOLTAGE) 
    1. Turn the power switch off.
    2. Connect the Techstream to the DLC3.
    3. Turn the power switch on (IG) and the Techstream on.
    4. Enter the following menus: Chassis / Electric Parking Brake / Data List.
    5. Check the values by referring to the table below.

      Chassis > Electric Parking Brake > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Tension1 Voltage Tension sensor 1 voltage display min.: 0.000 V
      max.: 5.000 V      		 0.5 to 4.5 V When not normal, tension sensor system may be malfunctioning.
      Tension2 Voltage Tension sensor 2 voltage display min.: 0.000 V
      max.: 5.000 V      		 0.5 to 4.5 V When not normal, tension sensor system may be malfunctioning.

      Chassis > Electric Parking Brake > Data List 

      Tester Display
      Tension1 Voltage
      Tension2 Voltage

      OK

      Display changes according to operation of the electric parking brake switch assembly.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    CHECK PARKING BRAKE ASSEMBLY. Refer to  INSPECTION [10/2017 - ] 

    Result: 

    NG 

    REPLACE PARKING BRAKE WITH BRACKET ACTUATOR ASSEMBLY. Refer to  REMOVAL [10/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

  5. CHECK HARNESS AND CONNECTOR (BECU CIRCUIT) 
    1. Turn the power switch off.
    2. Disconnect the parking brake ECU assembly connector.
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      L77-2 (BECU) - Body ground Power switch off 11 to 14 V

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE PARKING BRAKE ECU ASSEMBLY. Refer to  REMOVAL [10/2020 - 11/2021]  , or refer to  REMOVAL [11/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023] 

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

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