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 keys Engine Immobilizer System.
* If the transmission control ECU assembly is replaced, register the ECU code Engine Immobilizer System.
* If the ID code box (immobilizer 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 F50 certification ECU (smart key ECU assembly), F52 power management control ECU, F16 ID code box (immobilizer code ECU) and A36 transmission control ECU assembly 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 F50 certification ECU (smart key ECU assembly), F52 power management control ECU and F16 ID code box (immobilizer code ECU) connectors.

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

(c) After 10 seconds have elapsed, check if the DTC is stored again.

(d) 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 A36 transmission control ECU assembly connector.

(b) Disconnect the F52 power management control ECU connector.

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

(d) After 10 seconds have elapsed, check if the DTC is stored again.

(e) Recheck for DTCs.

Result:





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

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

(a) Reconnect the F52 power management control ECU connector.

(b) Disconnect the F16 ID code box (immobilizer code ECU) connector.

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

(d) After 10 seconds have elapsed, check if the DTC is stored again.

(e) Recheck for DTCs.

Result:





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

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