LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2019 >> LC 500 >> Repair and Diagnosis >> External Pages >> Different car >> Section 49 (Lin Communication System - Diagnostic Codes) >> Lin Communication System >> DTC B2785: Communication Malfunction between ECUs Connected by LIN [04/2013 - 09/2022] >> Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC B2785: Communication Malfunction between ECUs Connected by LIN [04/2013 - 09/2022]: Procedure

WARNING: This page does not describe the selected car, but rather 27 other vehicles, including the 2024 Lexus IS 500, 2024 Lexus IS 350, 2024 Lexus IS 300, 2023 Lexus IS 500, and 2023 Lexus IS 350. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - EACH ECU) 
    1. Disconnect the K6 certification ECU (smart key ECU assembly) connector.
    2. Disconnect the K28 steering lock ECU (steering lock actuator assembly) connector.
    3. Disconnect the K83 ID code box (immobiliser code ECU) connector.
    4. Measure the resistance according to the value(s) in the table below.
      NOTE:

      Make sure that each ECU is in sleep mode before performing the inspection. To enter sleep mode, turn the engine switch from on (IG) to off and wait for 180 seconds or more without operating any switches.

      Standard Resistance

      Tester Connection Condition Specified Condition
      K6-6 (LIN) - K28-5 (LIN) Engine switch off Below 1 Ω
      K6-6 (LIN) - K83-2 (LIN1) Engine switch off Below 1 Ω
      K6-6 (LIN) - Body ground Engine switch off 10 kΩ or higher
      K28-5 (LIN) - Body ground Engine switch off 10 kΩ or higher
      K83-2 (LIN1) - Body ground Engine switch off 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  2

  2. CHECK DTC OUTPUT (STEERING LOCK ECU (STEERING LOCK ACTUATOR ASSEMBLY)) 
    1. Reconnect the K6 certification ECU (smart key ECU assembly) connector.
    2. Reconnect the K83 ID code box (immobiliser code ECU) connector.
    3. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [04/2013 - ]

      Body Electrical > Smart Access > Clear DTCs 

    4. Recheck for DTCs.

      Body Electrical > Smart Access > Trouble Codes 

      Result

      Result Proceed to
      DTC B2785 is output A
      DTC B2785 is not output B

    Result: 

    B 

    REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR ASSEMBLY). Refer to  DISASSEMBLY [04/2013 - ] 

    Result: 

    A 

    See step  3

  3. CHECK DTC OUTPUT (ID CODE BOX (IMMOBILISER CODE ECU)) 
    1. Reconnect the K28 steering lock ECU (steering lock actuator assembly) connector.
    2. Disconnect the K83 ID code box (immobiliser code ECU) connector.
    3. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [04/2013 - ]

      Body Electrical > Smart Access > Clear DTCs 

    4. Recheck for DTCs.

      Body Electrical > Smart Access > Trouble Codes 

      Result

      Result Proceed to
      DTC B2785 is output A
      DTC B2785 is not output B

    Result: 

    A 

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [04/2013 - 08/2015]  , or refer to  REMOVAL [08/2015 - 09/2020]  , or refer to  REMOVAL [09/2020 - ] 

    Result: 

    B 

    REPLACE ID CODE BOX (IMMOBILISER CODE ECU). Refer to  REMOVAL [04/2013 - ] 

scientia non olet · About LEMON Manuals