DTC B27A5: Open in Front Floor Electrical Key Oscillator Circuit [10/2018 - 07/2022]: Procedure

1. 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.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

CONNECT CONNECTORS PROPERLY 

Result: 

OK 

See step  2

1. Disconnect the F44 certification ECU (smart key ECU assembly) connector.
2. Disconnect the F46 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
   F44-8 (CLG5) - F46-1 (ANTE5)	Always	Below 1 Ω
   F44-9 (CG5B) - F46-3 (CLGB)	Always	Below 1 Ω

4. Reconnect the F44 certification ECU (smart key ECU assembly) connector.

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR 

Result: 

OK 

See step  3

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Using an oscilloscope, check the waveform.

   OK

   Tester Connection	Condition	Tool Setting	Specified Condition
   F44-8 (CLG5) - F44-18 (E)	Procedure: Engine switch off Electrical key transmitter sub-assembly not inside vehicle Within 30 seconds of closing any door	2 V/DIV., 500 ms./DIV.	Pulse generation (See waveform)
   F44-9 (CG5B) - F44-18 (E)	Procedure: Engine switch off Electrical key transmitter sub-assembly not inside vehicle Within 30 seconds of closing any door	2 V/DIV., 500 ms./DIV.	Pulse generation (See waveform)

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE NO. 1 INDOOR ELECTRICAL KEY ANTENNA ASSEMBLY (FRONT FLOOR). Refer to  REMOVAL [10/2018 - ] 

Result: 

NG 

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY). Refer to  REMOVAL [10/2018 - 07/2022]