LIN Communication System

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 ECU system LIN bus lines. When the certification ECU (smart key ECU assembly) detects an error in communication with all the ECUs connected to the certification ECU system LIN bus lines at a set interval and 3 times in a row, DTC B2785 will be output.





WIRING DIAGRAM





INSPECTION PROCEDURE

HINT
When DTC B2785 and B2287 are output simultaneously, perform the troubleshooting for DTC B2785 first.

NOTICE:
- If the certification ECU (smart key ECU assembly) is replaced, register the keys and ECU communication ID Engine Immobiliser System (W/ Smart Key System).
- If the steering lock ECU (steering lock actuator assembly) is replaced, register the ECU code Engine Immobiliser System (W/ Smart Key System).
- If the ID code box (immobiliser code ECU) is replaced, register the ECU code and ECU communication ID Engine Immobiliser System (W/ Smart Key System).

PROCEDURE

1. CLEAR DTC

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

NEXT -- Continue to next step.

2. CHECK FOR DTC

(a) Recheck for the DTC Reading and Clearing Diagnostic Trouble Codes.

OK:

B2785 is not output.

NG -- CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - EACH ECU)

OK -- USE SIMULATION METHOD TO CHECK How To Proceed With Troubleshooting

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

(a) Disconnect the E22, E36, E39 and 2C 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.

4. CHECK FOR DTC (STEERING LOCK ECU)

(a) Reconnect the E36, E22 and 2C connectors.

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

(c) Recheck for the DTC.

Result:





B -- REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR ASSEMBLY)
A -- Continue to next step.

5. CHECK FOR DTC (ID CODE BOX)

(a) Reconnect the E39 connector.

(b) Disconnect the E22 connector.

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

(d) Recheck for the DTC.

Result:





B -- REPLACE ID CODE BOX (IMMOBILISER CODE ECU) Removal
A -- Continue to next step.

6. CHECK FOR DTC (MAIN BODY ECU)

(a) Reconnect the E22 connector.

(b) Disconnect the 2C connector.

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

(d) Recheck for the DTC.

OK:

B2785 is not output.

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

OK -- REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK)