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DTC B2785: Communication Malfunction between ECUs Connected by LIN [08/2013 - ]: Procedure

WARNING: This page is about a different car, the 2014 Lexus ES 300h. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - EACH ECU) 
    1. Disconnect the H58 certification ECU (smart key ECU assembly) connector.
    2. Disconnect the H18 steering lock ECU (steering lock actuator assembly) connector.
    3. Disconnect the H15 ID code box (immobilizer code ECU) connector.
    4. Disconnect the H2 power management control ECU connector.
    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      H58-12 (LIN) - H18-5 (LIN) Always Below 1 Ω
      H58-12 (LIN) - H2-11 (LIN2) Always Below 1 Ω
      H58-12 (LIN) - H15-2 (LIN1) Always Below 1 Ω
      H58-12 (LIN) - Body ground Always 10 kΩ or higher

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  2. CHECK DTC OUTPUT (STEERING LOCK ECU (STEERING LOCK ACTUATOR ASSEMBLY)) 
    1. Reconnect the H58 certification ECU (smart key ECU assembly) connector.
    2. Reconnect the H15 ID code box (immobilizer code ECU) connector.
    3. Reconnect the H2 power management control ECU connector.
    4. Clear the DTCs. Refer to DTC CHECK / CLEAR [08/2013 - ] .
    5. Recheck for DTCs.

      Result

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

    B → See step   5 

    A: Go to next step 

  3. CHECK DTC OUTPUT (POWER MANAGEMENT CONTROL ECU) 
    1. Reconnect the H18 steering lock ECU (steering lock actuator assembly) connector.
    2. Disconnect the H2 power management control ECU connector.
    3. Clear the DTCs. Refer to DTC CHECK / CLEAR [08/2013 - ] .
    4. Recheck for DTCs.

      Result

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

    B → See step   8 

    A: Go to next step 

  4. CHECK DTC OUTPUT (ID CODE BOX (IMMOBILIZER CODE ECU)) 
    1. Reconnect the H2 power management control ECU connector.
    2. Disconnect the H15 ID code box (immobilizer code ECU) connector.
    3. Clear the DTCs. Refer to DTC CHECK / CLEAR [08/2013 - ] .
    4. Recheck for DTCs.

      Result

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

    B → See step   6 

    A → See step   7 

  5. REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR ASSEMBLY). Refer to  DISASSEMBLY [08/2013 - ] 
  6. REPLACE ID CODE BOX (IMMOBILIZER CODE ECU). Refer to  REMOVAL [08/2013 - ] 
  7. REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [08/2013 - ] 
  8. REPLACE POWER MANAGEMENT CONTROL ECU. Refer to  REMOVAL [08/2013 - ] 
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