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DTC B2789: No Response from ID BOX [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 DTC OUTPUT 
    1. Clear the DTCs. Refer to DTC CHECK / CLEAR [08/2013 - ] .
    2. Recheck for DTCs.

      Result

      Result Proceed to
      Only B2789 is output A
      DTC B2789 and B2785 are output simultaneously B

      HINT: 

      When DTC B2789 and B2785 are output simultaneously, perform troubleshooting for DTC B2785 first.

    B → See step   7 

    A: Go to next step 

  2. CHECK HARNESS AND CONNECTOR (ID CODE BOX - AUXILIARY BATTERY AND BODY GROUND) 
    1. Disconnect the H15 ID code box (immobilizer code ECU).
    2. Measure the resistance and voltage according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      H15-5 (GND) - Body ground Always Below 1 Ω

      Standard Voltage

      Tester Connection Condition Specified Condition
      H15-1 (+B) - Body ground Power switch off 11 to 14 V

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  3. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - ID CODE BOX) 
    1. Disconnect the H58 certification ECU (smart key ECU assembly) connector.
    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      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 

  4. REPLACE ID CODE BOX (IMMOBILIZER CODE ECU) 
    1. Replace the ID code box (immobilizer code ECU). Refer to REMOVAL [08/2013 - ] .

    NEXT: Go to next step 

  5. CHECK DTC OUTPUT 
    1. Clear the DTCs. Refer to DTC CHECK / CLEAR [08/2013 - ] .
    2. Recheck for DTCs.

      OK

      DTC B2789 is not output.

    NG → See step   6 

    OK → END (ID CODE BOX (IMMOBILIZER CODE ECU) WAS DEFECTIVE) 

  6. REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [08/2013 - ] 
  7. GO TO DTC B2785. Refer to  DTC B2785: Communication Malfunction between ECUs Connected by LIN [08/2013 - ]