LIN COMMUNICATION SYSTEM, Diagnostic DTC:B278C

DTC Code DTC Name
B278C Lost Communication with Power Source Control

DESCRIPTION

This DTC is stored when LIN communication between the certification ECU and power management control ECU stops for 10 seconds or more.

DTC Code DTC Detection Condition Trouble Area
B278C No communication between the certification ECU and power management control ECU for 10 seconds or more.

  • Power management control ECU

  • Certification ECU

WIRING DIAGRAM

A003E4BE01

INSPECTION PROCEDURE

Note


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

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

  • Inspect the fuses and bulbs for circuits related to this system before performing the following inspection procedure.

Tech Tips

When the communication between the power management control ECU and certification ECU stops, DTC B2785 is also stored.

PROCEDURE


  1. CLEAR DTC


    1. Clear the DTCs Click here.


    NEXT

  2. CHECK FOR DTC


    1. Recheck for DTCs Click here.

      Result
      Result Proceed to
      DTC B278C is output A
      DTC B278C is not output B

    B

    USE SIMULATION METHOD TO CHECK Click here

    A

  3. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - POWER MANAGEMENT CONTROL ECU)

    A003DAAE01
    Text in Illustration
    *1

    Front view of wire harness connector

    (to Certification ECU)
    *2

    Front view of wire harness connector

    (to Power Management Control ECU)

    1. Disconnect the D54 and D75 ECU connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      D54-29 (LIN) - D75-24 (LIN2) Always Below 1 Ω
      D54-29 (LIN) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU - BATTERY AND BODY GROUND)

    A003DFRE01
    Text in Illustration
    *1

    Front view of wire harness connector

    (to Power Management Control ECU)

    1. Disconnect the D75 ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      D75-5 (GND2) - Body ground Always Below 1 Ω
      D75-6 (GND) - Body ground Always Below 1 Ω
      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      D75-1 (AM22) - Body ground Always 11 to 14 V
      D75-2 (AM21) - Body ground Always 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. REPLACE POWER MANAGEMENT CONTROL ECU


    1. Temporarily replace the power management control ECU with a new or normally functioning one Click here.

    2. Clear the DTCs Click here.


    NEXT

  6. CHECK FOR DTC


    1. Recheck for DTCs Click here.

      Result
      Result Proceed to
      DTC B278C is not output A
      DTC B278C is output B

    B

    REPLACE CERTIFICATION ECU

    A

    END (POWER MANAGEMENT CONTROL ECU IS DEFECTIVE)