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Home >> Lexus >> 2008 >> IS 250 RWD, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 40 (Networking) >> Lin Communication System >> DTC B2785 Communication Malfunction between ECUs Connected by LIN >> Inspection Procedure

Inspection Procedure

WARNING: This page is about a different car, the 2008 Lexus IS F. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
  • If the certification ECU (smart key ECU assembly) is replaced, register the key (See REGISTRATION ).
  • If the steering lock ECU (steering lock actuator assembly) is replaced, register the ECU code (See REGISTRATION ).
  • If the ID code box (immobilizer code ECU) is replaced, register the ECU code and ECU communication ID (See REGISTRATION ).
  1. CHECK FOR DTC 
    1. Clear the DTC (See DIAGNOSIS SYSTEM  ).
    2. Recheck for DTC

      OK: B2785 is not output. 

    NG: Go to step 2 

    OK: USE SIMULATION METHOD TO CHECK  (See HOW TO PROCEED WITH TROUBLESHOOTING )

  2. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - EACH ECU) 
    1. Disconnect the P33, J55, J69 and J29 ECU connectors.
      Fig 1: Identifying P33, J55, J69 And J29 ECU Connector Terminal
      G05754098Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the resistance and voltage according to the value(s) in the table below

      Standard Resistance 

      RESISTANCE REFERENCE

      Tester Connection Condition Specified Condition
      P33-10 (LIN) - J29-5 (LIN) Always Below 1 Ω
      P33-10 (LIN) - J55-30 (LIN1) Always Below 1 Ω
      P33-10 (LIN) - J69-3 (LIN1) Always Below 1 Ω
      P33-10 (LIN) - Body ground Always 10 kΩ or higher

      Standard Voltage 

      VOLTAGE SPECIFICATION

      Tester Connection Condition Specified Condition
      P33-10 (LIN) - Body ground Always Below 1 V

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to Next Step 

  3. CHECK FOR DTC (STEERING LOCK ECU) 
    1. Reconnect the P33, J55 and J69 connectors
    2. Clear the DTC (See DIAGNOSIS SYSTEM  ).
    3. Recheck for DTC

      Result 

      DTC RESULT REFERENCE

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

    B: REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR ASSEMBLY)  (See DISASSEMBLY )

    A: Go to Next Step 

  4. CHECK FOR DTC (ID CODE BOX) 
    1. Reconnect the J29 connector
    2. Disconnect the J69 connector.
    3. Clear the DTC (See DIAGNOSIS SYSTEM  )
    4. Recheck for DTC

      Result 

      DTC RESULT REFERENCE

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

    B: REPLACE ID CODE BOX (IMMOBILIZER CODE ECU)  (See REMOVAL )

    A: Go to Next Step 

  5. REPLACE POWER SOURCE CONTROL ECU 
    1. Replace the power source control ECU
  6. CHECK FOR DTC 
    1. Clear the DTC (See DIAGNOSIS SYSTEM  )
    2. Recheck for DTC

      OK: B2785 is not output. 

    NG: REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)  (See REMOVAL )

    OK: END (POWER SOURCE CONTROL ECU IS DEFECTIVE) 

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