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 10 seconds or more.

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

  • Power management control ECU

  • Certification ECU (smart key ECU assembly)

  • Wire harness or connector

  • AM2 fuse

WIRING DIAGRAM

A004VJAE08

CAUTION / NOTICE / HINT

Note


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

  • 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 H3 and H4 power management control ECU connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H3-6 (E1) - Body ground Always Below 1 Ω
      Standard Voltage
      Tester Connection Condition Specified Condition
      H3-1 (AM22) - Body ground Power switch off 11 to 14 V
      H4-7 (AM21) - Body ground Power switch off 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Disconnect the H1*1 or H143*2 certification ECU (smart key ECU assembly) connector.


      • *1: w/ Entry Function

      • *2: w/o Entry Function

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

      Standard Resistance
      w/ Entry Function
      Tester Connection Condition Specified Condition
      H1-29 (LIN) - H4-11 (LIN2) Always Below 1 Ω
      H1-29 (LIN) - Body ground Always 10 kΩ or higher
      w/o Entry Function
      Tester Connection Condition Specified Condition
      H143-29 (LIN) - H4-11 (LIN2) Always Below 1 Ω
      H143-29 (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.

    OK

    END (POWER MANAGEMENT CONTROL ECU WAS DEFECTIVE)

    NG

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)