ENGINE IMMOBILISER SYSTEM(w/ Entry and Start System), Diagnostic DTC:B278A

DTC Code DTC Name
B278A Short to GND in Immobiliser System Power Source Circuit

DESCRIPTION

This DTC is output when the engine switch power source supply line is open or shorted.

DTC Code DTC Detection Condition Trouble Area
B278A The engine switch power source supply line is open or shorted.

  • Harness or connector


  • Engine switch


  • Certification ECU (Smart key ECU)

WIRING DIAGRAM

A01X6D3E57
*1 Engine Switch
*2 Certification ECU

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - ENGINE SWITCH)

    A01WZ72E02
    *1 Front view of wire harness connector: (to Certification ECU (Smart Key ECU Assembly))
    *2 Front view of wire harness connector: (to Engine Switch)

    1. Disconnect the E29 ECU connector.

    2. Disconnect the E18 switch connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E29-30 (VC5) - E18-14 (VC5) Always Below 1 Ω
      E29-40 (AGND) - E18-8 (AGND)
      E29-30 (VC5) or E18-14 (VC5) - Body ground Always 10 kΩ or higher
      E29-40 (AGND) or E18-8 (AGND) - Body ground

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. REPLACE ENGINE SWITCH


    1. for 1GR-FE


      1. Temporarily replace the engine switch with a new one Click here.

    2. for 1UR-FE


      1. Temporarily replace the engine switch with a new one Click here.

    3. for 1VD-FTV


      1. Temporarily replace the engine switch with a new one Click here.

    4. for 3UR-FE


      1. Temporarily replace the engine switch with a new one Click here.


    NEXT

  3. CLEAR DTC


    1. Clear the DTCs Click here.


    NEXT

  4. CHECK FOR DTC


    1. Check for DTCs Click here.

      OK
      DTC B278A is not output.

    OK

    END (ENGINE SWITCH IS DEFECTIVE)

    NG

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)