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Home >> Lexus >> 2018 >> LC 500 >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> Electronically Controlled Brake System - Diagnostic Codes (Coupe) (4 Of 4) & Symptom Tests >> Electronically Controlled Brake System >> Brake Control Warning Light does not Come ON [03/2017 - ] >> Procedure

Brake Control Warning Light does not Come ON [03/2017 - ]: Procedure

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

      Refer to DIAGNOSIS SYSTEM [03/2017 - 06/2019] , or refer to DIAGNOSIS SYSTEM [06/2019 - 04/2020] , or refer to DIAGNOSIS SYSTEM [04/2020 - 11/2021] , or refer to DIAGNOSIS SYSTEM [11/2021 - 10/2022] , or refer to DIAGNOSIS SYSTEM [10/2022 - 05/2023] , or refer to DIAGNOSIS SYSTEM [05/2023 - ]

      Result

      Result Proceed to
      DTCs are not output. A
      DTCs are output. B

    Result: 

    INSPECT CAN COMMUNICATION SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [03/2017 - 09/2018]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [09/2018 - 05/2023]  , or refer to  HOW TO PROCEED WITH TROUBLESHOOTING [05/2023 - ] 

    Result: 

    See step  2

  2. PERFORM ACTIVE TEST USING TECHSTREAM (BRAKE WARNING LIGHT / YELLOW (MINOR MALFUNCTION)) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Select the Active Test on the Techstream.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 05/2023] , or refer to DATA LIST / ACTIVE TEST [05/2023 - ]

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      ECB Warning Light Brake warning light / yellow (minor malfunction) Warning light ON/OFF
      • Observe combination meter assembly
      • ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Active Test 

      Tester Display
      ECB Warning Light

      ECB: Electronically Controlled Brake System

    4. Select the Data List on the Techstream.

      Refer to DATA LIST / ACTIVE TEST [03/2017 - 05/2023] , or refer to DATA LIST / ACTIVE TEST [05/2023 - ]

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      ECB Warning Light Brake warning light / yellow (minor malfunction) ON or OFF ON: Warning light on
      OFF: Warning light off
      ECB: Electronically Controlled Brake System

      Chassis > ABS/VSC/TRAC > Data List 

      Tester Display
      ECB Warning Light

      ECB: Electronically Controlled Brake System

    5. Check the operating condition of the brake warning light / yellow (minor malfunction) when operating it using the Techstream.

      Result

      Result Proceed to
      Brake warning light / yellow (minor malfunction) in the Data List does not change using the Active Test. A
      Brake warning light / yellow (minor malfunction) in the Data List turns ON/OFF using the Active Test. B

    Result: 

    REPLACE SKID CONTROL ECU ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023]  , or refer to  REMOVAL [05/2023 - ] 

    Result: 

    See step  3

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

      Refer to DATA LIST / ACTIVE TEST [03/2017 - ]

      Body Electrical > Combination Meter > Active Test 

      Tester Display
      Indicat. Lamp ECB

      ECB: Electronically Controlled Brake System

    3. Check the combination meter assembly.

      OK

      The brake warning light / yellow (minor malfunction) turns on or off in accordance with the Techstream operation.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE SKID CONTROL ECU ASSEMBLY. Refer to  REMOVAL [03/2017 - 05/2023]  , or refer to  REMOVAL [05/2023 - ] 

    Result: 

    NG 

    INSPECT METER / GAUGE SYSTEM. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [03/2017 - ]