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 engine switch, the certification ECU (smart key ECU assembly) stores this DTC.

DTC Code DTC Detection Condition Trouble Area DTC Output Confirmation Operation
B278A A short to GND in the power supply of the transponder key amplifier of the engine switch (VC5 - VC5) (1 trip detection logic*).

  • Wire harness or connector


  • Engine switch


  • Certification ECU (smart key ECU assembly)

 With the shift lever in P, the key held near the engine switch and an engine start operation is performed by pressing and holding the engine switch when the key battery is depleted.

Vehicle Condition and Fail-safe Operation when Malfunction Detected
Vehicle Condition when Malfunction Detected Fail-safe Operation when Malfunction Detected
Engine cannot be started when key battery is depleted by holding key near engine switch and pressing and holding engine switch with shift lever in P -
Related Data List and Active Test
DTC Code Data List and Active Test
B278A -

WIRING DIAGRAM

A01W1JGE40
*a Engine Switch
*b Certification ECU (Smart Key ECU Assembly)

CAUTION / NOTICE / HINT

Note


  • When using the GTS with the vehicle engine switch off, connect the GTS to the vehicle 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 the 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 performing repairs, perform the operation that fulfills the DTC output confirmation operation, and then confirm that no DTCs are output again.

PROCEDURE


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


    1. Disconnect the H56 certification ECU (smart key ECU assembly) connector.

    2. Disconnect the H44 engine switch connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H56-1 (VC5) - H44-10 (VC5) Always Below 1 Ω
      H56-24 (AGND) - H44-6 (AGND) Always Below 1 Ω
      H44-10 (VC5) - Body ground Always 10 kΩ or higher
      H44-6 (AGND) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)


    1. Reconnect the H44 engine switch and H56 certification ECU (smart key ECU assembly) connectors.

    2. A01VZGPE02
      Text in Illustration
      *a

      Component with harness connected

      (Engine Switch)

      Using an oscilloscope, check the waveform.

      Tech Tips

      Perform this inspection on the engine switch side.

      Measurement Condition
      Item Content
      Tester Connection H44-10 (VC5) - H44-6 (AGND)
      Tool Setting 2 V/DIV., 200 ms./DIV.
      Condition Engine switch off, key not in cabin, within 30 seconds after engine switch pressed
      OK
      Waveform is output normally (refer to illustration).
      Result
      Result Proceed to
      OK (for 2GR-FE) A
      OK (for 2AR-FE) B
      OK (for 6AR-FSE) C
      NG D

    A

    REPLACE ENGINE SWITCH Click here

    B

    REPLACE ENGINE SWITCH Click here

    C

    REPLACE ENGINE SWITCH Click here

    D

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)