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

WIRING DIAGRAM

A01V049E24
*a from Auxiliary Battery
*b Certification ECU (Smart Key ECU Assembly)
*c Power Management Control ECU
*d LIN Communication Line

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) or power management control ECU is replaced, refer to Service Bulletin.

  • 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 DTC OUTPUT


    1. Clear the DTC Click here.

    2. Recheck for DTCs.

      Result
      Result Proceed to
      Only B278C is output A
      DTC B278C and B2785 are output simultaneously B

      Tech Tips

      When DTC B278C and B2785 are output simultaneously, perform troubleshooting for DTC B2785 first.


    B

    GO TO DTC B2785 Click here

    A

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


    1. Disconnect the F55 and F56 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
      F55-6 (E1) - Body ground Always Below 1 Ω
      Standard Voltage
      Tester Connection Condition Specified Condition
      F55-1 (AM22) - Body ground Ignition switch off 11 to 14 V
      F56-7 (AM21) - Body ground Ignition switch off 11 to 14 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Disconnect the F47 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
      F47-12 (LIN) - F58-11 (LIN2) Always Below 1 Ω
      F47-12 (LIN) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. REPLACE POWER MANAGEMENT CONTROL ECU


    1. Replace the power management control ECU Click here.


    NEXT

  5. 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)