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

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
B278A A short to GND in the power supply of the transponder key amplifier of the engine switch (VC5 - VC5) detected. (1 trip detection logic)*

  • Engine switch

  • Certification ECU (smart key ECU assembly)

  • Harness or connector

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 transmitter battery is depleted by holding transmitter 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

A01WYUBE30
*1 CODE
*2 Engine Switch
*3 Certification ECU (Smart Key ECU Assembly)

CAUTION / NOTICE / HINT

Note


  • When using the GTS with the engine 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. Using an oscilloscope, check the waveform.

      A01X3Y5E02
      Text in Illustration
      *a

      Component with harness connected

      (Engine Switch)

      		 - -
      Measurement Condition
      Tester Connection Condition Tool Setting Specified Condition
      E123-10 (VC5) - E123-6 (AGND) Engine switch off, key not in cabin, within 30 seconds after engine switch pressed 2 V/DIV., 200 ms./DIV. Pulse generation
      OK
      The waveform is similar to that shown in the illustration.
      Result
      Result Proceed to
      OK (for 3UR-FE) A
      OK (for 1UR-FE) B
      OK (for 1GR-FE) C
      OK (for 1VD-FTV) D
      NG E

    A

    REPLACE ENGINE SWITCH Click here

    B

    REPLACE ENGINE SWITCH Click here

    C

    REPLACE ENGINE SWITCH Click here

    D

    REPLACE ENGINE SWITCH Click here

    E

  2. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU [SMART KEY ECU ASSEMBLY] - ENGINE SWITCH)


    1. Disconnect the E130 certification ECU (smart key ECU assembly) connector.

    2. Disconnect the E123 engine switch connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E130-15 (VC5) - E123-10 (VC5) Always Below 1 Ω
      E130-12 (AGND) - E123-6 (AGND) Always Below 1 Ω
      E130-15 (VC5) or E123-23 (VC5) - Body ground Always 10 kΩ or higher
      E130-12 (AGND) or E123-6 (AGND) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)


    1. Reconnect the E130 certification ECU (smart key ECU assembly) connector.

      A01X2I1E01
      Text in Illustration
      *a

      Component with harness connected

      (Certification ECU [Smart Key ECU Assembly])

      		 - -

    2. Reconnect the E123 engine switch connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      E130-15 (VC5) - E130-12 (AGND) Engine switch off, brake pedal not depressed, 30 seconds or more elapsed after driver door opened and then closed Below 1 V
      Result
      Result Proceed to
      OK (for 3UR-FE) A
      OK (for 1UR-FE) B
      OK (for 1GR-FE) C
      OK (for 1VD-FTV) D
      NG E

    A

    REPLACE ENGINE SWITCH Click here

    B

    REPLACE ENGINE SWITCH Click here

    C

    REPLACE ENGINE SWITCH Click here

    D

    REPLACE ENGINE SWITCH Click here

    E

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)