B2791

ENGINE IMMOBILISER: ENGINE IMMOBILISER SYSTEM: B2791: Communication Condition Failure between ECM

DTC B2791 - Communication Condition Failure between ECM

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.





WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK DTC OUTPUT
(a) Delete the DTC Reading and Clearing Diagnostic Trouble Codes.
(b) Recheck for DTC Reading and Clearing Diagnostic Trouble Codes.
Result:






B -- USE SIMULATION METHOD TO CHECK
A -- Continue to next step.
2. ECU COMMUNICATION ID REGISTRATION
(a) Register the ECU communication ID between the ID code box and ECM Engine Immobilizer System.
(b) Recheck for DTC Reading and Clearing Diagnostic Trouble Codes.
Result:






B -- END
A -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (ID CODE BOX - ECM)





(a) Disconnect the J69 ECU and A6 ECM connectors.
(b) Measures the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
4. REPLACE ID CODE BOX
(a) Replace the ID code box.
NEXT -- Continue to next step.
5. ELECTRICAL KEY REGISTRATION
(a) Register the electrical key code in the certification ECU Engine Immobilizer System.
NEXT -- Continue to next step.
6. ECU COMMUNICATION ID REGISTRATION
(a) Register the ECU communication ID between the ID code box and ECM Engine Immobilizer System.
NEXT -- Continue to next step.
7. CHECK DTC OUTPUT
(a) Delete the DTC Reading and Clearing Diagnostic Trouble Codes.
(b) Recheck for DTC Reading and Clearing Diagnostic Trouble Codes.
Result:






A -- REPLACE ECM
B -- END