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Home >> Lexus >> 2021 >> LS 500 Base, AWD >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> Electronically Controlled Brake System (W/ Vacuum Brake Booster) - Diagnostic Codes (4 Of 4) & Symptom Tests >> ELECTRONICALLY CONTROLLED BRAKE SYSTEM (w/ Vacuum Brake Booster) >> Brake Warning Light does not Come ON [12/2017 - 09/2018] >> Procedure

Brake Warning Light does not Come ON [12/2017 - 09/2018]: Procedure

  1. CHECK CAN COMMUNICATION SYSTEM 
    1. Check if CAN communication system DTCs are output.

      Refer to DIAGNOSIS SYSTEM [12/2017 - 09/2018]

      Result

      Proceed to
      DTC is not output
      DTC is output

    Result: 

    DTC is output 

    CHECK CAN COMMUNICATION SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [12/2017 - 09/2018] 

    Result: 

    DTC is not output 

    See step  2

  2. PERFORM ACTIVE TEST USING TECHSTREAM (BRAKE SYSTEM WARNING LIGHT (RED INDICATOR)) 
    1. Turn the engine switch off.
    2. Connect the Techstream to the DLC3.
    3. Turn the engine switch on (IG).
    4. Turn the Techstream on.
    5. Enter the following menus: Chassis / ABS/VSC/TRAC / Active Test.
    6. According to the display on the Techstream, perform the Active Test.

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      Brake Warning Light Brake system warning light (red indicator) Warning light OFF/ON Observe combination meter
      Vehicle condition: Vehicle stopped
    7. When performing the Brake Warning Light Active Test, check Brake Warning Light in the Data List.

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Brake Warning Light Brake system warning light (red indicator) OFF or ON OFF: Warning light off
      ON: Warning light on
      -

      Chassis > ABS/VSC/TRAC > Active Test 

      Active Test Display
      Brake Warning Light
      Data List Display
      Brake Warning Light

      Result

      Result Proceed to
      Brake system warning light (red indicator) in the Data List does not change using the Active Test A
      Brake system warning light (red indicator) in the Data List turns ON/OFF using the Active Test B

    Result: 

    A 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [12/2017 - 09/2018] 

    Result: 

    B 

    See step  3

  3. INSPECT COMBINATION METER ASSEMBLY 
    1. Turn the engine switch off.
    2. Perform Active Test of the combination meter assembly using the Techstream.

      Body Electrical > Combination Meter > Active Test 

      Tester Display
      Brake Warning
    3. Check the combination meter assembly.

      OK

      The brake system warning light (red indicator) turns on or off in accordance with the Techstream.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE BRAKE ACTUATOR ASSEMBLY. Refer to  REMOVAL [12/2017 - 09/2018] 

    Result: 

    NG 

    INSPECT METER / GAUGE SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [12/2017 - 10/2023]