SMART KEY SYSTEM (for Entry Function), Diagnostic DTC:B27A5

DTC Code DTC Name
B27A5 Open in Front Floor Electrical Key Oscillator Circuit

DESCRIPTION

The certification ECU (smart key ECU assembly) generates a request signal and transmits the signal to the No. 1 indoor electrical key antenna assembly (front floor). For the No. 1 indoor electrical key antenna assembly (front floor) to detect when the electrical key transmitter sub-assembly is inside the vehicle, the signal from the certification ECU (smart key ECU assembly) requesting a response from the electrical key transmitter sub-assembly is transmitted inside the vehicle. DTC B27A5 is stored by the certification ECU (smart key ECU assembly) when an open circuit is detected between the certification ECU (smart key ECU assembly) and No. 1 indoor electrical key antenna assembly (front floor) (between terminals CLG5 and ANTE5, or terminals CG5B and CLGB).

DTC Code DTC Detection Condition Trouble Area DTC Output Confirmation Operation
B27A5 An open circuit is detected in the circuit between the certification ECU (smart key ECU assembly) and No. 1 indoor electrical key antenna assembly (front floor) (CLG5 - ANTE5, CG5B - CLGB) (1 trip detection logic*).

  • Wire harness or connector

  • No. 1 indoor electrical key antenna assembly (front floor)

  • Certification ECU (smart key ECU assembly)

 Any time
Vehicle Condition and Fail-safe Operation when Malfunction Detected
Vehicle Condition when Malfunction Detected Fail-safe Operation when Malfunction Detected

When electrical key transmitter sub-assembly is in front seat area:

  • Power source mode does not change when engine switch pressed

  • Electrical key transmitter sub-assembly locked inside vehicle

 -
Related Data List and Active Test
DTC Code Data List and Active Test
B27A5 Key diagnostic mode can be used to perform troubleshooting

WIRING DIAGRAM

A011RXKE47

INSPECTION PROCEDURE

Note

  • The smart key system (for Entry Function) uses a multiplex communication system (LIN communication system) and the CAN communication system. Inspect the communication function by following How to Proceed with Troubleshooting Click here. Troubleshoot the smart key system (for Entry Function) after confirming that the communication systems are functioning properly.

  • When using the Techstream with the engine switch off to troubleshoot:

    Connect the Techstream to the DLC3 and turn a courtesy light switch on and off at 1.5-second intervals until communication between the Techstream and vehicle begins.

  • Before replacing the certification ECU (smart key ECU assembly), refer to the smart key system (for Entry Function) precaution Click here.

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

  • The No. 1 indoor electrical key antenna assembly (front floor) has an antenna coil between ANTE5 and CLGB terminals.

PROCEDURE

  1. CHECK CONNECTOR CONNECTION

    1. Turn the engine switch off.

    2. Check that the connectors are properly connected to the certification ECU (smart key ECU assembly) and No. 1 indoor electrical key antenna assembly (front floor).

      OK
      Connectors are properly connected.
    NG

    CONNECT CONNECTORS PROPERLY

    OK

  2. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - NO. 1 INDOOR ELECTRICAL KEY ANTENNA ASSEMBLY)

    1. Disconnect the A43 and I78 certification ECU (smart key ECU assembly) connectors.

    2. Disconnect the I46 No. 1 indoor electrical key antenna assembly (front floor) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I78-3 (CLG5) - I46-1 (ANTE5) Always Below 1 Ω
      I78-2 (CG5B) - I46-3 (CLGB) Always Below 1 Ω
      A43-11 (E) - Body ground Always Below 1 Ω
      I78-3 (CLG5) or I46-1 (ANTE5) - Body ground Always 10 kΩ or higher
      I78-2 (CG5B) or I46-3 (CLGB) - Body ground Always 10 kΩ or higher
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (OUTPUT TO NO. 1 INDOOR ELECTRICAL KEY ANTENNA ASSEMBLY)

    1. Connect the A43 and I78 certification ECU (smart key ECU assembly) connectors.

      A011TCRE27
      Text in Illustration
      *1 Waveform - -
      *a

      Component with harness connected

      (Certification ECU (smart key ECU assembly))

      		 *b Within approximately 30 seconds from when the door is closed
      *c After approximately 30 seconds from when the door is closed - -

    2. Connect the I46 No. 1 indoor electrical key antenna assembly (front floor) connector.

    3. Using an oscilloscope, check the waveform.

      OK
      Tester Connection Switch Condition Tool Setting Specified Condition
      I78-3 (CLG5) - A43-11 (E)

      Procedure:

      1. Engine switch off

      2. Electrical key transmitter sub-assembly not inside vehicle

      3. Door is open

      4. Door is closed

      5. Within 30 seconds

      		 2 V/DIV., 500 ms/DIV. Pulse generation (See waveform)
      I78-2 (CG5B) - A43-11 (E)

      Procedure:

      1. Engine switch off

      2. Electrical key transmitter sub-assembly not inside vehicle

      3. Door is open

      4. Door is closed

      5. Within 30 seconds

      		 2 V/DIV., 500 ms/DIV. Pulse generation (See waveform)
    NG

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) Click here

    OK

  4. REPLACE NO. 1 INDOOR ELECTRICAL KEY ANTENNA ASSEMBLY (FRONT FLOOR)

    1. Temporarily replace the No. 1 indoor electrical key antenna assembly (front floor) with a new or known good one Click here.

    NEXT

  5. CLEAR DTC

    1. Clear the DTCs Click here.

    NEXT

  6. CHECK FOR DTC

    1. Check for DTCs Click here.

      OK
      DTC B27A5 is not output.
    NG

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) Click here

    OK

    END (NO. 1 INDOOR ELECTRICAL KEY ANTENNA ASSEMBLY (FRONT FLOOR) WAS DEFECTIVE)