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

A011XMIE12

INSPECTION PROCEDURE

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 keys Click here.

  • When using the Techstream to troubleshoot with the power switch off:

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

PROCEDURE

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

    1. Disconnect the I3 and I4 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
      I3-6 (E1) - Body ground Always Below 1 Ω
      Standard Voltage
      Tester Connection Condition Specified Condition
      I3-1 (AM22) - Body ground Power switch off 11 to 14 V
      I4-7 (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 I87 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
      I87-12 (LIN) - I4-11 (LIN2) Always Below 1 Ω
      I87-12 (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) Click here

    OK

    END (POWER MANAGEMENT CONTROL ECU WAS DEFECTIVE)