Lexus IS250 · Service Manual SECURITIES

B2785

Diagnostic trouble codes

DESCRIPTION

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

WIRING DIAGRAM

B124172E02

1. CHECK HARNESS AND CONNECTOR (LIN COMMUNICATION LINE AND BODY GROUND)
B106651E09

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

  1. 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
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


2. CHECK DTC OUTPUT

  1. Delete the DTCs (Click here).

  1. Recheck for DTCs (Click here).

    Result:
    Result
    		 Proceed to
    B2785 and B2786 output or B2786 output reoccurs
    		 A
    B2785 and B2789 output or B2789 output reoccurs
    		 B
    B2785 output reoccurs
    		 C



B
Go to step 6

C
Go to step 10
A


3. REPLACE STEERING LOCK ECU

  1. Replace the steering lock ECU.


NEXT


4. ECU CODE REGISTRATION

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


NEXT


5. CHECK DTC OUTPUT

  1. Check for DTCs (Click here).

    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

  1. Register the electrical key code in the certification ECU.


NEXT


8. ECU COMMUNICATION ID REGISTRATION

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


NEXT


9. CHECK DTC OUTPUT

  1. Check for DTCs (Click here).

    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

  1. Replace the certification ECU.


NEXT


11. KEY REGISTRATION

  1. Register the electrical key code in the certification ECU.


NEXT


12. ECU COMMUNICATION ID REGISTRATION

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


NEXT


13. CHECK DTC OUTPUT

  1. Check for DTCs (Click here).

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



B
END
A


14. REPLACE POWER SOURCE CONTROL ECU

  1. Replace the power source control ECU.


NEXT


15. ECU CODE REGISTRATION

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


NEXT


16. CHECK DTC OUTPUT

  1. Check for DTCs (Click here).

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



B
END
A


17. REPLACE STEERING LOCK ECU

  1. Replace the steering lock ECU.


NEXT


18. ECU CODE REGISTRATION

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


NEXT


19. CHECK DTC OUTPUT

  1. Check for DTCs (Click here).

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



B
END
A

REPLACE IMMOBILISER CODE ECU


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