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 Short to GND detected 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 electrical key transmitter sub-assembly 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 electrical key transmitter sub-assembly 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

Refer to B2784.

Click here

CAUTION / NOTICE / HINT

Note


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

  • After performing repairs, 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.

      A003LNAC62
      *a

      Component with harness connected

      (Power Switch)

      		 - -

      Tech Tips

      Perform this inspection on the power switch side.

      Measurement Condition
      Tester Connection Condition Tool Setting Specified Condition
      I53-10 (VC5) - I53-6 (AGND) Power switch off, key not in cabin, within 30 seconds of pressing power switch 2 V/DIV., 200 ms./DIV. Pulse generation
      OK
      The waveform is similar to that shown in the illustration.
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE POWER SWITCH Click here

    NG

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


    1. Disconnect the I1 certification ECU (smart key ECU assembly) connector.

    2. Disconnect the I53 power switch connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I1-7 (VC5) - I53-10 (VC5) Always Below 1 Ω
      I1-7 (VC5) or I53-10 (VC5) - Body ground Always 10 kΩ or higher
      I1-11 (AGND) - I53-6 (AGND) Always Below 1 Ω
      I1-11 (AGND) or I53-6 (AGND) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)


    1. Reconnect the I1 certification ECU (smart key ECU assembly) connector.

    2. Reconnect the I53 power switch connector.

    3. A003O5PC48
      *a

      Component with harness connected

      (Certification ECU (Smart Key ECU Assembly))

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      I1-7 (VC5) - I1-11 (AGND) Power switch off, brake pedal not depressed, 30 seconds or more after driver door opened and then closed Below 1 V
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE POWER SWITCH Click here

    NG

    REPLACE CERTIFICATION ECU (SMART KEY ASSEMBLY)