DTC    B2785    Communication Malfunction between ECUs Connected by LIN

for Preparation Click here


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.

DTC No.
DTC Detection Condition
Trouble Area
B2785
  1. Errors in LIN communication between ECUs or an open or short in communication lines
  2. LIN communication from the certification ECU (smart key ECU assembly) detects errors in communication 3 times in a row.
  1. Certification ECU (smart key ECU assembly)
  2. Power management control ECU
  3. Steering lock ECU (steering lock actuator assembly)
  4. ID code box (immobiliser code ECU)
  5. Wire harness or connector

WIRING DIAGRAM


B203743E45


INSPECTION PROCEDURE

NOTICE:
  1. If the certification ECU (smart key ECU assembly), ID code box (immobiliser code ECU), steering lock ECU (steering lock actuator assembly) or power management control ECU is replaced, refer to the Registration (Click here).
  2. When using the Techstream to troubleshoot with the ignition 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.
1.CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - EACH ECU)

  1. Disconnect the G54, G58, G49 and G50 connectors.

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

    Standard Resistance:
    Tester Connection
    		Condition
    		Specified Condition
    G54-12 (LIN) - G50-5 (LIN)
    		Always
    		Below 1 Ω
    G54-12 (LIN) - G58-11 (LIN2)
    		Always
    		Below 1 Ω
    G54-12 (LIN) - G49-2 (LIN1)
    		Always
    		Below 1 Ω
    G54-12 (LIN) - Body ground
    		Always
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


2.CHECK DTC OUTPUT (STEERING LOCK ECU (STEERING LOCK ACTUATOR ASSEMBLY))

  1. Reconnect the G54, G58 and G49 connectors.

  1. Clear the DTC (Click here).

  1. Recheck for DTCs.

    Result:
    Result
    		Proceed to
    DTC B2785 is output
    		A
    DTC B2785 is not output
    		B


B
REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR ASSEMBLY) (Click here)
A


3.CHECK DTC OUTPUT (POWER MANAGEMENT CONTROL ECU)

  1. Reconnect the G50 connector.

  1. Disconnect the G58 connector.

  1. Clear the DTC (Click here).

  1. Recheck for DTCs.

    Result:
    Result
    		Proceed to
    DTC B2785 is output
    		A
    DTC B2785 is not output
    		B


B
REPLACE POWER MANAGEMENT CONTROL ECU (Click here)
A


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

  1. Reconnect the G58 connector.

  1. Disconnect the G49 connector.

  1. Clear the DTC (Click here).

  1. Recheck for DTCs.

    Result:
    Result
    		Proceed to
    DTC B2785 is output
    		A
    DTC B2785 is not output
    		B


B
REPLACE ID CODE BOX (IMMOBILISER CODE ECU) (Click here)
A

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (Click here)