ENTRY AND START 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 certification ECU (smart key ECU assembly) 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 No.	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*1).	Wire harness or connector No. 1 Indoor electrical key antenna assembly (front floor) Certification ECU (smart key ECU assembly)	Any time*2

*1: Only output while a malfunction is present.
*2: Only when the vehicle is stopped.

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 engine switch pressed Key locked inside vehicle	-

Related Data List and Active Test
DTC No.	Data List and Active Test
B27A5	Key diagnostic mode can be used to perform troubleshooting

WIRING DIAGRAM

CAUTION / NOTICE / HINT

Note

When using the intelligent tester with the engine 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.
The entry and start system (for Entry Function) uses a 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.
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 does not reoccur by performing the "DTC Output Confirmation Operation".
No. 1 indoor electrical key antenna assembly (front floor) has an antenna coil between CLG3 and CLGB terminals.

PROCEDURE

CHECK CONNECTOR CONNECTION CONDITION
1. Turn the engine switch off.
2. Check that the connectors are properly connected to the certification ECU (smart key ECU assembly) and the No. 1 indoor electrical key antenna assembly (front floor).
  
  OK
  
  Connectors are properly connected.
NG
CONNECT CONNECTORS PROPERLY

OK

OK
Connectors are properly connected.

INSPECT ELECTRICAL KEY WIRE HARNESS

Remove the electrical key wire harness.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
FF2-5 - FF2-1	Always	Below 1 Ω
FF2-4 - FF2-2	Always	Below 1 Ω

Reinstall the electrical key wire harness.

REPLACE ELECTRICAL KEY WIRE HARNESS

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

Disconnect the F63 and F65 certification ECU (smart key ECU assembly) connector.
Disconnect the F62 No. 1 indoor electrical key antenna assembly (front floor) connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
F63-3 (CLG5) - F62-1 (CLG3)	Always	Below 1 Ω
F63-2 (CG5B) - F62-3 (CLGB)	Always	Below 1 Ω
F65-11 (E) - Body ground	Always	Below 1 Ω
F63-3 (CLG5) - Body ground	Always	10 kΩ or higher
F63-2 (CG5B) - Body ground	Always	10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

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

Text in Illustration
*a	Component with harness connected (Certification ECU (smart key ECU assembly))	*b	Waveform
*c	Door open	*d	After approximately 30 seconds from when the door is closed

Reconnect the F63 and F65 certification ECU (smart key ECU assembly) connector.
Reconnect the F62 No. 1 indoor electrical key antenna assembly (front floor) connector.

Using an oscilloscope, check the waveform.

Tech Tips

Check that the entry cancel function, which is one of the customizing settings of the entry and start system, is not set Click here.

Tester Connection

Switch Condition

Tool Setting

Specified Condition

F63-3 (CLG5) - F65-11 (E)

Procedure:

Engine switch off
Door is open
Door is closed
30 seconds elapse
Electrical key transmitter sub-assembly not inside vehicle

2 V/DIV., 500 ms/DIV.

Pulse generation

(See waveform)

F63-2 (CG5B) - F65-11 (E)

Procedure:

Engine switch off
Door is open
Door is closed
30 seconds elapse
Electrical key transmitter sub-assembly not inside vehicle

2 V/DIV., 500 ms/DIV.

Pulse generation

(See waveform)

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

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
CHECK DTC OUTPUT
1. Clear the DTCs Click here.
2. Recheck for DTCs Click here.
  
  OK
  
  DTC B27A5 is not output.
OK
END (NO. 1 INDOOR ELECTRICAL KEY ANTENNA ASSEMBLY (FRONT FLOOR) WAS DEFECTIVE)

NG
REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)