Lexus IS250 · Service Manual SECURITIES

B2791

Diagnostic trouble codes

DESCRIPTION

This DTC is output when the ID code box dose not respond to a verification request signal from the ECM.

HINT:
If the engine switch is turned off immediately after an engine start, this DTC is also detected.

DTC No.
 DTC Detection Condition
 Trouble Area
B2791
 ID code box dose not respond to a verification request signal from ECM
  1. Wire harness
  2. ID code box
  3. ECM

WIRING DIAGRAM

B118531E03

INSPECTION PROCEDURE


1. CHECK DTC OUTPUT

  1. Delete the DTC (Click here).

  1. Recheck for DTC (Click here).

    Result:
    Result
    		 Proceed to
    B2791 is output
    		 A
    No DTC is output
    		 B



B
USE SIMULATION METHOD TO CHECK
A


2. ECU COMMUNICATION ID REGISTRATION

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

  1. Recheck for DTC (Click here).

    Result:
    Result
    		 Proceed to
    B2791 is output
    		 A
    No DTC is output
    		 B



B
END
A


3. CHECK HARNESS AND CONNECTOR (ID CODE BOX - ECM)

  1. B111364E11
    Disconnect the J69 ECU and A6 ECM connectors.

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

    Standard resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    J69-6 (EFIO) - A6-6 (IMI)
    		 Always
    		 Below 1 Ω
    J69-6 (EFIO) - Body ground
    		 Always
    		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


4. REPLACE ID CODE BOX

  1. Replace the ID code box.


NEXT


5. KEY REGISTRATION

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


NEXT


6. ECU COMMUNICATION ID REGISTRATION

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


NEXT


7. CHECK DTC OUTPUT

  1. Delete the DTC (Click here).

  1. Recheck for DTC (Click here).

    Result:
    Result
    		 Proceed to
    B2791 is output
    		 A
    No DTC is output
    		 B



A
REPLACE ECM
B

END


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