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 No. 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

A01NFSQE03

INSPECTION PROCEDURE

Note


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

  • 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 (POWER MANAGEMENT CONTROL ECU - BATTERY AND BODY GROUND)


    1. Disconnect the F97 and F98 power management control ECU connectors.

      A01NCWXE01

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F97-5 (E01) - Body ground Always Below 1 Ω
      F98-5 (E02) - Body ground Always Below 1 Ω
      Standard Voltage
      Tester Connection Condition Specified Condition
      F97-1 (AM22) - Body ground Always 11 to 14 V
      F98-7 (AM21) - Body ground Always 11 to 14 V
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Power Management Control ECU)

      		 *2

      Front view of wire harness connector

      (to Power Management Control ECU)

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. A01NCU2E01
      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 F58 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
      F58-29 (LIN) - F98-11 (LIN2) Always Below 1 Ω
      F58-29 (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 (for LHD: Click here (for RHD: 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)