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 (smart key ECU assembly) and power management control ECU stops for more than 10 seconds.

DTC Code DTC Detection Condition Trouble Area
B278C No communication between the certification ECU (smart key ECU assembly) and power management control ECU for more than 10 seconds.

  • Power management control ECU

  • Certification ECU (Smart key ECU assembly)

  • Wire harness or connector

  • AM2 fuse

WIRING DIAGRAM

A01EMF4E04

INSPECTION PROCEDURE

Note


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

  • When using the GTS to troubleshoot with the ignition switch off:

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

PROCEDURE


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


    1. A01EKDPE02
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Power Management Control ECU)

      Disconnect the D43 ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      D43-5 (GND2) - Body ground Always Below 1 Ω
      D43-6 (GND) - Body ground Always Below 1 Ω
      Standard Voltage
      Tester Connection Condition Specified Condition
      D43-1 (AM22) - Body ground Always 11 to 14 V
      D43-2 (AM21) - Body ground Always 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. A01EMAKE05
      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 Power Management Control ECU)

      Disconnect the D25 ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      D25-29 (LIN) - D43-24 (LIN2) Always Below 1 Ω
      D25-29 (LIN) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. REPLACE POWER MANAGEMENT CONTROL ECU


    1. Replace the power management control ECU Click here.


    NEXT

  4. CHECK DTC OUTPUT


    1. Clear the DTC Click here.

    2. Recheck for DTCs.

      OK
      DTC B278C is not output.

    NG

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

    OK

    END (POWER MANAGEMENT CONTROL ECU WAS DEFECTIVE)