B2785

NETWORKING: LIN COMMUNICATION SYSTEM: B2785: Communication Malfunction between ECUs Connected by LIN
B2785 - Communication Malfunction between ECUs Connected by LIN

DESCRIPTION

The certification ECU (smart key ECU assembly) monitors communication between all the ECUs connected to the certification bus lines. When the certification ECU (smart key ECU assembly) detects errors in communication with all the ECUs connected to the certification bus lines at a set interval and 3 times in a row, DTC B2785 will be stored.





WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
* If the certification ECU (smart key ECU assembly) is replaced, register the key Engine Immobilizer System.
* If the transmission control ECU assembly is replaced, register the ECU code Engine Immobilizer System.
* If the ID code box (immobiliser code ECU) is replaced, register the ECU code and ECU communication ID Engine Immobilizer System.
* When using the Techstream to troubleshoot with the power switch off:
Connect the Techstream to the DLC3, and turn the courtesy switch on and off at 1.5-second intervals until communication between the Techstream and vehicle begins.

PROCEDURE

1. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - EACH ECU)

(a) Disconnect the H1, H4, H22 and A22 connectors.

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

Standard Resistance:





Standard Voltage:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

2. CHECK DTC OUTPUT (TRANSMISSION CONTROL ECU ASSEMBLY)

(a) Reconnect the H1, H4 and H22 connectors.

(b) Clear the DTC Reading and Clearing Diagnostic Trouble Codes.

(c) Recheck for DTCs.

Result:





B -- REPLACE TRANSMISSION CONTROL ECU ASSEMBLY Removal
A -- Continue to next step.

3. CHECK DTC OUTPUT (POWER MANAGEMENT CONTROL ECU)

(a) Reconnect the A22 connector.

(b) Disconnect the H4 connector.

(c) Clear the DTC Reading and Clearing Diagnostic Trouble Codes.

(d) Recheck for DTCs.

Result:





B -- REPLACE POWER MANAGEMENT CONTROL ECU Removal
A -- Continue to next step.

4. CHECK DTC OUTPUT (ID CODE BOX (IMMOBILISER CODE ECU))

(a) Reconnect the H4 connector.

(b) Disconnect the H22 connector.

(c) Clear the DTC Reading and Clearing Diagnostic Trouble Codes.

(d) Recheck for DTCs.

Result:





B -- REPLACE ID CODE BOX (IMMOBILISER CODE ECU) Removal

A -- REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) Removal