DTC B27A5: Open in Front Floor Electrical Key Oscillator Circuit: Procedure

1. Turn the engine switch off.
2. Check that the connectors are properly connected to the certification ECU and indoor No. 1 electrical key antenna (front floor).

   OK

   Connectors are properly connected.

NG → CONNECT CONNECTORS PROPERLY 

OK: Go to next step 

1. Disconnect the F77 antenna connector.
2. Disconnect the F79 ECU connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   F77-1 (CLG3) - F79-7 (CLG5)	Always	Below 1 Ω
   F77-3 (CLGB) - F79-8 (CG5B)	Always	Below 1 Ω
   F79-7 (CLG5) - Body ground	Always	10 kΩ or higher
   F79-8 (CG5B) - Body ground	Always	10 kΩ or higher
   F79-15 (E) - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Measure the voltage according to the value(s) in the table below.
   Fig 1: Identifying F79 Connector

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   TEXT IN ILLUSTRATION
   
   

   *a

   Component with harness connected (Certification ECU)

   -

   -

   OK

   Tester Connection	Switch Condition	Specified Condition
   F79-7 (CLG5) - F79-15 (E)	Engine switch off, all doors closed, key not in cabin and lock sensor off → on	No pulse generation → Pulse generation
   F79-8 (CG5B) - F79-15 (E)	Engine switch off, all doors closed, key not in cabin and lock sensor off → on	No pulse generation → Pulse generation

NG → See step   6 

OK: Go to next step 

1. Temporarily replace the indoor No. 1 electrical key antenna (front floor) with a new or normally functioning one. Refer to REMOVAL .

NEXT: Go to next step 

1. Clear the DTCs. Refer to DTC CHECK / CLEAR .
2. Check for DTCs. Refer to DTC CHECK / CLEAR .

   OK

   DTC B27A5 is not output.

NG → See step   6 

OK → END (INDOOR NO. 1 ELECTRICAL KEY ANTENNA ASSEMBLY IS DEFECTIVE)