LIN COMMUNICATION SYSTEM, Diagnostic DTC:B2785

DTC Code DTC Name
B2785 Communication Malfunction between ECUs Connected by LIN

DESCRIPTION

The certification ECU (smart key ECU assembly) monitors communication between all the ECUs connected to the certification bus lines. When the certification ECU (smart key ECU assembly) detects errors in communication with all the ECUs connected to the certification bus lines at a set interval and 3 times in a row, DTC B2785 will be stored.

DTC No. DTC Detection Condition Trouble Area
B2785

  • Errors in LIN communication between ECUs and an open or short in communication lines

  • LIN communication from the certification ECU (smart key ECU assembly) detects errors in communication 3 times in a row.

  • Certification ECU (smart key ECU assembly)

  • Power management control ECU

  • Transmission control ECU assembly

  • ID code box (immobiliser code ECU)*1

  • Wire harness or connector

WIRING DIAGRAM

A01JAN3E21

INSPECTION PROCEDURE

Note


  • If the certification ECU (smart key ECU assembly) is replaced, register the key.

  • If the transmission control ECU assembly is replaced, register the ECU code.

  • If the ID code box (immobiliser code ECU) is replaced, register the ECU code and ECU communication ID.

  • When using the intelligent tester to troubleshoot with the power switch off:

    Connect the intelligent tester to the DLC3, and turn the courtesy switch on and off at 1.5-second intervals until communication between the intelligent tester and vehicle begins.

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - EACH ECU)


    1. Disconnect the L62, L6, L10*1 and A24 connectors.


      • *1: w/ Airbag Cut-off Switch

      A01JAHGE02

    2. Measure the resistance and voltage according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      L62-29 (LIN) - A24-24 (LIN) Always Below 1 Ω
      L62-29 (LIN) - L6-11 (LIN2) Always Below 1 Ω
      L62-29 (LIN) - L10-3 (LIN1)*1 Always Below 1 Ω
      L62-29 (LIN) - Body ground Always 10 kΩ or higher
      Standard Voltage
      Tester Connection Condition Specified Condition
      L62-29 (LIN) - Body ground Always Below 1 V

      • *1: w/ Airbag Cut-off Switch

      Text in Illustration
      *1

      Front view of wire harness connector

      (to Certification ECU (Smart Key ECU Assembly))

      		 *2

      Front view of wire harness connector

      (to ID code box (Immobiliser Code ECU))
      *3

      Front view of wire harness connector

      (to Power Management Control ECU)

      		 *4

      Front view of wire harness connector

      (to Transmission Control ECU Assembly)
      *5 w/ Airbag Cut-off Switch - -

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. CHECK DTC OUTPUT (TRANSMISSION CONTROL ECU ASSEMBLY)


    1. Reconnect the L62, L6 and L10*1 connectors.


      • *1: w/ Airbag Cut-off Switch

    2. Clear the DTC Click here.

    3. Recheck for DTCs.

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

    B

    REPLACE TRANSMISSION CONTROL ECU ASSEMBLY Click here

    A

  3. CHECK DTC OUTPUT (POWER MANAGEMENT CONTROL ECU)


    1. Reconnect the A24 connector.

    2. Disconnect the L6 connector.

    3. Clear the DTC Click here.

    4. Recheck for DTCs.

      Result
      Result Proceed to
      DTC B2785 is output (w/ Airbag Cut-off Switch) A
      DTC B2785 is output (w/o Airbag Cut-off Switch) B
      DTC B2785 is not output C

    B

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

    C

    REPLACE POWER MANAGEMENT CONTROL ECU Click here

    A

  4. CHECK DTC OUTPUT (ID CODE BOX (IMMOBILISER CODE ECU))


    1. Reconnect the L6 connector.

    2. Disconnect the L10 connector.

    3. Clear the DTC Click here.

    4. Recheck for DTCs.

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

    B

    REPLACE ID CODE BOX (IMMOBILISER CODE ECU)

    A

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)