DTC No.	DTC Detection Condition	Trouble Area
B2785	LIN communication from certification ECU stops for a certain amount of time Open or short in wire harness between ECUs	Wire harness Certification ECU ID code box Power source control ECU Steering lock ECU
B2786	Certification ECU does not receive LIN communication from steering lock ECU for 10 seconds	Wire harness Certification ECU Steering lock ECU
B2789	Certification ECU does not receive LIN communication from ID code box Open or short in wire harness between ECUs	Wire harness Certification ECU ID code box

WIRING DIAGRAM

Dtc B2785 Communication Malfunction Between Ecus Connected By Lin. ENGINE IMMOBILISER. Lexus IS250 IS220d GSE20 ALE20

1.CHECK HARNESS AND CONNECTOR (LIN COMMUNICATION LINE AND BODY GROUND)

Dtc B2785 Communication Malfunction Between Ecus Connected By Lin. ENGINE IMMOBILISER. Lexus IS250 IS220d GSE20 ALE20

Disconnect the P33, J29, J55 and J69 ECU connectors.

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

Standard resistance:

Tester Connection	Condition	Specified Condition
P33-10 (LIN) - J69-3 (LIN1)	Always	Below 1 Ω
P33-10 (LIN) - J55-30 (LIN1)	Always	Below 1 Ω
P33-10 (LIN) - 29-5 (LIN)	Always	Below 1 Ω
P33-10 (LIN) - Body ground	Always	10 kΩ or higher

NG

Go to step 6

C

Go to step 10

A

3.REPLACE STEERING LOCK ECU

Replace the steering lock ECU.

NEXT

4.ECU CODE REGISTRATION

Register the ECU code between the ECUs connected by LIN communication.

NEXT

5.CHECK DTC OUTPUT

Check for DTCs .

Result:
Result Proceed to
B2785 and B2786 output or B2786 output reoccurs A
Neither B2785 and B2786 output nor B2786 output reoccurs B

B

END

A

REPLACE CERTIFICATION ECU

6.REPLACE ID CODE BOX

NEXT

7.KEY REGISTRATION

Register the electrical key code in the certification ECU.

NEXT

8.ECU COMMUNICATION ID REGISTRATION

Register the ECU communication ID between the ID code box and ECM.

NEXT

9.CHECK DTC OUTPUT

Check for DTCs .

Result:
Result Proceed to
B2785 and B2789 output or B2789 output reoccurs A
Neither B2785 and B2789 output nor B2789 output reoccurs B

B

END

A

REPLACE CERTIFICATION ECU

10.REPLACE CERTIFICATION ECU

Replace the certification ECU.

NEXT

11.KEY REGISTRATION

Register the electrical key code in the certification ECU.

NEXT

12.ECU COMMUNICATION ID REGISTRATION

Register the ECU communication ID between the ID code box and ECM.

NEXT

13.CHECK DTC OUTPUT

Check for DTCs .

Result:
Result Proceed to
B2785 output reoccurs A
B2785 output does not reoccur B

B

END

A

14.REPLACE POWER SOURCE CONTROL ECU

Replace the power source control ECU.

NEXT

15.ECU CODE REGISTRATION

Register the ECU code between the ECUs connected by LIN communication.

NEXT

16.CHECK DTC OUTPUT

Check for DTCs .

Result:
Result Proceed to
B2785 output reoccurs A
B2785 output does not reoccur B

B

END

A

17.REPLACE STEERING LOCK ECU

Replace the steering lock ECU.

NEXT

18.ECU CODE REGISTRATION

Register the ECU code between the ECUs connected by LIN communication.

NEXT

19.CHECK DTC OUTPUT

Check for DTCs .

Result:
Result Proceed to
B2785 output reoccurs A
B2785 output does not reoccur B

B

END

A

REPLACE ID CODE BOX

LEXUS IS250, IS220d / GSE20 ALE20

ENGINE IMMOBILISER

Lexus IS250 IS220d GSE20 ALE20

ENGINE IMMOBILISER SYSTEM for 4GR-FSE