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) detected. (1 trip detection logic*)

  • Power switch

  • Certification ECU (smart key ECU assembly)

  • Wire harness or connector

DTC output confirmation operation:


  • With the shift lever in P 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 transmitter near power switch and pressing and holding power switch with shift lever in P -
Related Data List and Active Test
DTC No. Data List and Active Test
B278A -

WIRING DIAGRAM

A0022TZE08
*1 CODE
*2 Power Switch
*3 Certification ECU (Smart Key ECU Assembly)

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. Using an oscilloscope, check the waveform.

      A0022ZYC04
      *a

      Component with harness connected

      (Power Switch)

      		 - -
      Measurement Condition
      Tester Connection Condition Tool Setting Specified Condition
      K50-10 (VC5) - K50-6 (AGND) Power switch off, key not in cabin, within 30 seconds after power switch pressed 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 K8 certification ECU (smart key ECU assembly) connector.

    2. Disconnect the K50 power switch connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K8-16 (VC5) - K50-10 (VC5) Always Below 1 Ω
      K8-13 (AGND) - K50-6 (AGND) Always Below 1 Ω
      K8-16 (VC5) or K50-10 (VC5) - Body ground Always 10 kΩ or higher
      K8-13 (AGND) or K50-6 (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 K8 certification ECU (smart key ECU assembly) connector.

    2. Reconnect the K50 power switch connector.

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

      A00223HC03
      *a

      Component with harness connected

      (Certification ECU (Smart Key ECU Assembly))

      		 - -
      Standard Voltage
      Tester Connection Condition Specified Condition
      K8-16 (VC5) - K8-13 (AGND) Power switch off, brake pedal not depressed, 30 seconds or more elapsed 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 ECU ASSEMBLY)