DTC B279A-12: Engine Immobilizer System Circuit Short to Battery [11/2023 - ]: Procedure

Pre-procedure1

1. Turn the ignition switch off.

   Procedure1

2. Check that the connectors are properly connected to the hybrid vehicle control ECU and ID code box (immobilizer code ECU).

   OK

   Connectors are properly connected.

   Result

   Proceed to
   OK
   NG

   Post-procedure1

3. None

Result: 

NG 

CONNECT CONNECTORS PROPERLY 

Result: 

OK 

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)	*b	Waveform 1
   *c	Approximately 160 ms.	*d	Approximately 270 ms.

   OK

   Tester Connection	Condition	Tool Setting	Specified Condition
   H67-25 (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 1)

   Result

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

Result: 

B 

REPLACE HYBRID VEHICLE CONTROL ECU. Refer to  REMOVAL [11/2023 - ] 

Result: 

A 

See step  3

Pre-procedure1

1. Disconnect the H67 hybrid vehicle control ECU connector.
2. Disconnect the H53 ID code box (immobilizer code ECU) connector.

   Procedure1

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

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   H53-4 (EFIO) - H67-25 (IMI)	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

   Post-procedure1

4. None

Result: 

OK 

REPLACE ID CODE BOX (IMMOBILIZER CODE ECU). Refer to  REMOVAL [11/2023 - ] 

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR