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. Detection Item DTC Detection Condition Trouble Area
B278C Lost Communication with Power Source Control 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

A01MRTME04
*a Certification ECU (Smart Key ECU Assembly)
*b Power Management Control ECU
*c LIN Communication Line

CAUTION / NOTICE / HINT

Note


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

  • If the certification ECU (smart key ECU assembly) or power management control ECU is replaced, refer to Service Bulletin.

  • When using the GTS with the power switch off, connect the GTS to the DLC3 and turn a courtesy light switch on and off at intervals of 1.5 seconds or less until communication between the GTS and the vehicle begins. Then select Model Code "KEY REGIST" under manual mode and enter the following menus: Body Electrical / Entry&Start(CAN). While using the GTS, periodically turn a courtesy light switch on and off at intervals of 1.5 seconds or less to maintain communication between the GTS and the vehicle.

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - POWER MANAGEMENT CONTROL ECU)


    1. Disconnect the K8 certification ECU (smart key ECU assembly) connector.

    2. Disconnect the K33 power management control ECU connector.

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

      Note

      Make sure that each ECU is in sleep mode before performing the inspection. To enter sleep mode, turn the power switch from on (IG) to off and wait for 60 seconds or more without operating any switches.

      Standard Resistance
      Tester Connection Condition Specified Condition
      K33-11 (LIN2) - K8-21 (LIN) Power switch off Below 1 Ω
      K33-11 (LIN2) - Body ground Power switch off 10 kΩ or higher
      K8-21 (LIN) - Body ground Power switch off 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Disconnect the K32 power management control ECU connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      K33-7 (AM21) - K32-6 (E1) Power switch off 11 to 14 V
      K32-1 (AM22) - K32-6 (E1) Power switch off 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K32-6 (E1) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. REPLACE POWER MANAGEMENT CONTROL ECU


    1. Replace the power management control ECU.

      Click here

      Result
      Proceed to
      NEXT

    NEXT

  4. REGISTER ECU CODE REGISTRATION


    1. Register the recognition codes in the ECUs.

      Tech Tips

      Refer to Service Bulletin.

      Result
      Proceed to
      NEXT

    NEXT

  5. CHECK DTC OUTPUT


    1. Clear the DTCs.

      Click here


      Body Electrical > Entry&Start > Clear DTCs

    2. Recheck for DTCs.


      Body Electrical > Entry&Start > Trouble Codes
      OK
      DTC B278C is not output.
      Result
      Proceed to
      OK
      NG

    OK

    END (POWER MANAGEMENT CONTROL ECU WAS DEFECTIVE)

    NG

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)