DTC B279A-12: Engine Immobiliser System Circuit Short to Battery [02/2019 - ]: Procedure

1. Turn the ignition switch off.
2. Check that the connectors are properly connected to the hybrid vehicle control ECU assembly and transponder key ECU assembly.

   OK

   Connectors are properly connected.

   Result

   Result	Proceed to
   The connectors are properly connected	A
   The connectors are not properly connected	B

Result: 

B 

CONNECT CONNECTORS PROPERLY 

Result: 

A 

See step  2

1. Using an oscilloscope, check the waveform.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Component with harness connected (Hybrid Vehicle Control ECU Assembly)	*b	Waveform
   *c	Approximately 160 ms.	*d	Approximately 270 ms.

   Measurement Condition

   Tester Connection	Condition	Tool Setting	Specified Condition
   A30-10 (IMI) - Body ground	Within 3 seconds of hybrid control system start or within 3 seconds of ignition switch turned to ON after cable disconnected and reconnected to auxiliary battery	2 V/DIV., 500 ms./DIV.	Pulse generation (See waveform)

   Result

   Result	Proceed to
   11 to 14 V	A
   Below 1 V	B
   Normal waveform

Result: 

B 

REPLACE HYBRID VEHICLE CONTROL ECU ASSEMBLY. Refer to  REMOVAL [02/2019 - 10/2019]  , or refer to  REMOVAL [10/2019 - 08/2020]  , or refer to  REMOVAL [08/2020 - 12/2021]  , or refer to  REMOVAL [12/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023]  , or refer to  REMOVAL [10/2023 - ] 

Result: 

A 

See step  3

1. Disconnect the A30 hybrid vehicle control ECU assembly connector.
2. Disconnect the G52 transponder key ECU assembly connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   G52-11 (EFIO) - A30-10 (IMI)	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE TRANSPONDER KEY ECU ASSEMBLY. Refer to  REMOVAL [02/2019 - 10/2019]  , or refer to  REMOVAL [10/2019 - 08/2020]  , or refer to  REMOVAL [08/2020 - 12/2021]  , or refer to  REMOVAL [12/2021 - 10/2022]  , or refer to  REMOVAL [10/2022 - 10/2023]  , or refer to  REMOVAL [10/2023 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR