PUSH-BUTTON START SYSTEM, 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 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*).

  • 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 key is in front seat area:


  • Power source mode does not change when power switch pressed

  • Key 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

A003W3QE33

INSPECTION PROCEDURE

Note


  • When using the intelligent tester with the power switch off, perform either of the following: 1) Turn a courtesy light switch on and off at intervals of 1.5 seconds or less until communication between the intelligent tester and vehicle begins, or 2) connect the intelligent tester to the vehicle, select the vehicle type under manual mode, and then enter the following menus:

    for Power Source Control: Body / Power Source Control / DTC.

    for Entry&Start: Body / Entry&Start / DTC.

  • The push-button start system uses multiplex communication. First perform the inspections in "How to Proceed with Troubleshooting" to confirm that there are no communication malfunctions before proceeding with troubleshooting Click here

  • After performing repairs, perform the operation that fulfills the DTC output confirmation operation, and then confirm that no DTCs are output again.

  • When replacing the certification ECU (smart key ECU assembly), registration must be performed refer to the Service Bulletin.

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

PROCEDURE


  1. 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.

    NG

    CONNECT CONNECTORS PROPERLY

    OK

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


    1. Disconnect the H143 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
      H143-7 (CLG5) - H74-1 (CLG3) Always Below 1 Ω
      H143-8 (CG5B) - H74-3 (CLGB) Always Below 1 Ω
      H143-15 (E) - Body ground Always Below 1 Ω
      H143-7 (CLG5) or H74-1 (CLG3) - Body ground Always 10 kΩ or higher
      H143-8 (CG5B) or H74-3 (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 [FRONT FLOOR])


    1. Connect the H143 certification ECU (smart key ECU assembly) connector.

      A003YFWE26
      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
      H143-7 (CLG5) - H143-15 (E)

      Procedure:


      1. Power switch off

      2. Door is open

      3. Door is closed

      4. 30 seconds elapse

      		 2 V/DIV., 500 ms/DIV. Pulse generation (See waveform)
      H143-8 (CG5B) - H143-15 (E)

      Procedure:


      1. Power switch off

      2. Door is open

      3. Door is closed

      4. 30 seconds elapse

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

    NG

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

    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 normally functioning 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)

    OK

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