DTC B279A-12: Engine Immobilizer System Circuit Short to Battery [11/2021 - ]: Procedure

Pre-procedure1

1. Turn the ignition switch off.

   Procedure1

2. Check that the connectors are properly connected to the ECM 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. Check that the engine starts.

   OK

   Engine starts normally.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [11/2021 - ] 

Result: 

NG 

See step  3

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

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Component with harness connected (ID Code Box (Immobilizer Code ECU))

   Standard Voltage

   Tester Connection	Condition	Specified Condition
   D62-4 (EFIO) - Body ground	Engine switch on (IG)	11 to 14 V

   Result

   Proceed to
   OK
   NG

Result: 

NG 

See step  5

Result: 

OK 

See step  4

1. Using an oscilloscope, check the waveform.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   *a	Component with harness connected ID Code Box (Immobilizer Code ECU)	*b	Waveform
   *c	Approximately 160 ms.	*d	Approximately 270 ms.

   OK

   Tester Connection	Condition	Tool Setting	Specified Condition
   D62-4 (EFIO) - Body ground	Within 3 seconds of engine 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

   Proceed to
   OK
   NG

Result: 

OK 

REPLACE ECM 

for A25A-FKS: Refer to REMOVAL [11/2021 - ]

for T24A-FTS: Refer to REMOVAL [11/2021 - ]

Result: 

NG 

REPLACE ID CODE BOX (IMMOBILIZER CODE ECU). Refer to  REMOVAL [11/2021 - ] 

Pre-procedure1

1. Disconnect the A20*1 or A19*2 ECM connector.
   1. *1: for A25A-FKS
   2. *2: for T24A-FTS
2. Disconnect the D62 ID code box (immobilizer code ECU) connector.

   Procedure1

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

   Standard Resistance

   FOR A25A-FKS
   
   

   Tester Connection	Condition	Specified Condition
   D62-4 (EFIO) - A20-26 (IMI)	Always	Below 1 Ω

   FOR T24A-FTS
   
   

   Tester Connection	Condition	Specified Condition
   D62-4 (EFIO) - A19-38 (IMI)	Always	Below 1 Ω

   Result

   Proceed to
   OK
   NG

   Post-procedure1

4. None

Result: 

OK 

REPLACE ECM 

for A25A-FKS: Refer to REMOVAL [11/2021 - ]

for T24A-FTS: Refer to REMOVAL [11/2021 - ]

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR