IMMOBILISER SYSTEM, Diagnostic DTC:B278A

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

DESCRIPTION

When there is a short to GND in the power supply for the transponder key amplifier of the power switch, the certification ECU (smart key ECU assembly) stores this DTC.

DTC No. Detection Item DTC Detection Condition Trouble Area Note
B278A Short to GND in Immobiliser System Power Source Circuit A short to GND in the power supply of the transponder key amplifier of the power switch (VC5 - VC5) (1 trip detection logic*).

  • Power switch

  • Wire harness or connector

  • Certification ECU (smart key ECU assembly)

DTC output confirmation operation:


  • With the park (P) selected and the key held near the power switch, a hybrid control system start operation is performed by pressing and holding the power switch when the transmitter battery is depleted.

Vehicle Condition and Fail-safe Operation when Malfunction Detected
Vehicle Condition when Malfunction Detected Fail-safe Operation when Malfunction Detected
Hybrid control system cannot be started when transmitter battery is depleted by holding key near power switch and pressing and holding power switch with park (P) selected -
Related Data List and Active Test
DTC No. Data List and Active Test
B278A -

WIRING DIAGRAM

A013B5DE01
*1 Certification ECU (Smart Key ECU Assembly)
*2 Power Switch

CAUTION / NOTICE / HINT

Note


  • 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.

  • Before replacing the certification ECU (smart key ECU assembly), refer to Service Bulletin.

  • After repair, confirm that no DTCs are output by performing "DTC Output Confirmation Operation."

PROCEDURE


  1. CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)


    1. A0139WNC04
      *a

      Component with harness connected

      (Power switch)

      Using an oscilloscope, check the waveform.

      Tech Tips

      Perform this inspection on the power switch side.

      Measurement Condition
      Item Content
      Tester Connection E36-10 (VC5) - E36-6 (AGND)
      Tool Setting 2 V/DIV., 200 ms./DIV.
      Condition Power switch off, key not in cabin, within 30 seconds of pressing power switch
      OK
      The waveform is similar to that shown in the illustration.
      Result
      Result Proceed to
      OK A
      NG B

    A

    REPLACE POWER SWITCH Click here

    B

  2. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - POWER SWITCH)


    1. Disconnect the E116 and E117 certification ECU (smart key ECU assembly) connectors.

    2. Disconnect the E36 power switch connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E116-9 (VC5) - E36-10 (VC5) Always Below 1 Ω
      E117-6 (AGND) - E36-6 (AGND) Always Below 1 Ω
      E36-10 (VC5) - Body ground Always 10 kΩ or higher
      E116-9 (VC5) - Body ground Always 10 kΩ or higher
      E36-6 (AGND) - Body ground Always 10 kΩ or higher
      E117-6 (AGND) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE CERTIFICATION ECU (SMART KEY ASSEMBLY)

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR