Networking. Dtc B2785 Communication Malfunction Between Ecus Connected By Lin

Power Source Network. Corolla. Zre142 Aze141

Networking. Corolla. Zre142 Aze141

DESCRIPTION

CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU - EACH ECU)

CHECK FOR DTC (STEERING LOCK ECU)

CHECK FOR DTC (ID CODE BOX)

CHECK FOR DTC (MAIN BODY ECU)

DTC 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.

DTC No.	DTC Detection Condition	Trouble Area
B2785	Error in LIN communication between ECUs and an open or short in communication lines LIN communication from the certification ECU (smart key ECU assembly) stops for a set amount of time or more	Certification ECU (smart key ECU assembly) Main body ECU (instrument panel junction block) Steering lock ECU (steering lock actuator assembly) ID code box (immobiliser code ECU) Wire harness or connector

WIRING DIAGRAM

Corolla. Zre142 Aze141.Networking.Lin Communication System.
Dtc
B2785 Communication Malfunction Between Ecus Connected By Lin

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 (COROLLA_ZRE142 RM000000QYF05AX.html).
If the steering lock ECU (steering lock actuator assembly) is replaced, register the ECU code (COROLLA_ZRE142 RM000000QYF05AX.html).
If the ID code box (immobiliser code ECU) is replaced, register the ECU code and ECU communication ID (COROLLA_ZRE142 RM000000QYF05AX.html).

1.CLEAR DTC

Clear the DTC (COROLLA_ZRE142 RM000002XHS04WX.html).

NEXT

2.CHECK FOR DTC

Recheck for the DTC (COROLLA_ZRE142 RM000002XHS04WX.html).
OK:
B2785 is not output.

Go to step 3

USE SIMULATION METHOD TO CHECK (COROLLA_ZRE142 RM000000UZ108OX.html)

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

Disconnect the E22, E36, E39 and 2C connectors.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
E36-10 (LIN) - E39-5 (LIN)	Always	Below 1 Ω
E36-10 (LIN) - E22-3 (LIN1)	Always	Below 1 Ω
E36-10 (LIN) - 2C-12 (LIN1)	Always	Below 1 Ω
E36-10 (LIN) - Body ground	Always	10 kΩ or higher

Standard Voltage:

Tester Connection	Condition	Specified Condition
E36-10 (LIN) - Body ground	Always	Below 1 V

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.CHECK FOR DTC (STEERING LOCK ECU)

Reconnect the E36, E22 and 2C connectors.

Clear the DTC (COROLLA_ZRE142 RM000002XHS04WX.html).

Recheck for the DTC.
Result:
Result
Proceed to
B2785 is output
A
B2785 is not output
B

REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR ASSEMBLY)

A

5.CHECK FOR DTC (ID CODE BOX)

Reconnect the E39 connector.

Disconnect the E22 connector.

Clear the DTC (COROLLA_ZRE142 RM000002XHS04WX.html).

Recheck for the DTC.
Result:
Result
Proceed to
B2785 is output
A
B2785 is not output
B

REPLACE ID CODE BOX (IMMOBILISER CODE ECU) (COROLLA_ZRE142 RM000003G05004X.html)

A

6.CHECK FOR DTC (MAIN BODY ECU)

Reconnect the E22 connector.

Disconnect the 2C connector.

Clear the DTC (COROLLA_ZRE142 RM000002XHS04WX.html).

Recheck for the DTC.
OK:
B2785 is not output.

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (COROLLA_ZRE142 RM000003G0O004X.html)

REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK)