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ENTRY AND START SYSTEM (for Entry Function), Diagnostic DTC:B27A5

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DTC Code DTC Name
B27A5 Open in Front Floor Electrical Key Oscillator Circuit
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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 key is inside the vehicle, the signal from the certification ECU (smart key ECU assembly) requesting a response from the key 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 CLG3, 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 - CLG3, CG5B - CLGB) (1 trip detection logic*).

  • Harness or connector

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

  • Certification ECU (smart key ECU assembly)

 Any time

Table 1. Vehicle Condition and Fail-safe Operation when Malfunction Detected
Vehicle Condition when Malfunction Detected Fail-safe Operation when Malfunction Detected

When key is in front seat area:


  • Power source mode does not change when power switch pressed

  • Key locked inside vehicle

 -
Table 2. Related Data List and Active Test
DTC Code Data List and Active Test
B27A5 Key diagnostic mode can be used to perform troubleshooting
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WIRING DIAGRAM

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INSPECTION PROCEDURE

Note:

  • The entry and start 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 entry and start system (for Entry Function) after confirming that the communication systems are functioning properly.

  • When using the intelligent tester with the power switch off to troubleshoot:

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

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

  • After repair, confirm DTC not reoccur with performing the "DTC Output Confirmation Operation".

  • No. 1 indoor electrical key antenna assembly (front floor) has an antenna coil between CLG3 and CLGB terminals.

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PROCEDURE


  1. Click here

    CHECK CONNECTOR CONNECTION


    1. Turn the power 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.

  2. Click here

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


    1. Disconnect the H1 certification ECU (smart key ECU assembly) connector.

    2. Disconnect the H74 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
      H1-7 (CLG5) - H74-1 (CLG3) Always Below 1 Ω
      H1-8 (CG5B) - H74-3 (CLGB) Always Below 1 Ω
      H1-15 (E) - Body ground Always Below 1 Ω
      H1-7 (CLG5) or H74-1 (CLG3) - Body ground Always 10 kΩ or higher
      H1-8 (CG5B) or H74-3 (CLGB) - Body ground Always 10 kΩ or higher

  3. Click here

    CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (OUTPUT TO NO. 1 INDOOR ELECTRICAL KEY ANTENNA [FRONT FLOOR])


    1. A003YFWE23

      Connect the H1 certification ECU (smart key ECU assembly) connector.

      Table 3. Text in Illustration
      *1 Waveform - -
      *a

      Component with harness connected

      (Certification ECU (Smart Key ECU Assembly))

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

    2. Connect the H74 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
      H1-7 (CLG5) - H1-15 (E)

      Procedure:


      1. Power switch off

      2. Key not inside vehicle

      3. Door is open

      4. Door is closed

      5. 30 seconds elapse

      		 2 V/DIV., 500 ms/DIV. Pulse generation (See waveform)
      H1-8 (CG5B) - H1-15 (E)

      Procedure:


      1. Power switch off

      2. Key not inside vehicle

      3. Door is open

      4. Door is closed

      5. 30 seconds elapse

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

  4. Click here

    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 normally functioning one (Click here).


  5. Click here

    CLEAR DTC


    1. Clear the DTCs (Click here).


  6. Click here

    CHECK FOR DTC


    1. Check for DTCs (Click here).

      OK
      DTC B27A5 is not output.

  7. Click here

    CONNECT CONNECTORS PROPERLY

  8. Click here

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  9. Click here

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

  10. Click here

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