NETWORKING: LIN COMMUNICATION SYSTEM: B2785; Communication Malfunction between ECUs Connected by LIN; 2022 - 2024 MY RAV4 RAV4 HV [12/2021

Last Modified: 01-30-2024	6.11:8.1.0	Doc ID: RM1000000021HPW
Model Year Start: 2022	Model: RAV4	Prod Date Range: [12/2021 - ]
Title: NETWORKING: LIN COMMUNICATION SYSTEM: B2785; Communication Malfunction between ECUs Connected by LIN; 2022 - 2024 MY RAV4 RAV4 HV [12/2021 - ]

DTC

B2785

Communication Malfunction between ECUs Connected by LIN

DESCRIPTION

If the certification ECU (smart key ECU assembly) detects a communication error with an ECU connected to the certification bus lines for 7 seconds or more, DTC B2785 will be stored.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area
B2785	Communication Malfunction between ECUs Connected by LIN	Errors in LIN communication between ECUs or an open or short in communication lines. The certification ECU (smart key ECU assembly) detects a communication error with an ECU connected to the certification bus lines for 7 seconds or more.	Certification ECU (smart key ECU assembly) ID code box (immobiliser code ECU) Harness or connector

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Before performing the inspection, check that DTC B2786 or B278C is not output.
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When using the Techstream with the ignition switch off, connect the Techstream to the DLC3 and turn a courtesy light switch on and off at intervals of 1.5 seconds or less until communication between the Techstream and the vehicle begins. Then select Model Code "KEY REGIST" under manual mode and enter the following menus: Body Electrical / Smart Key. While using the Techstream, periodically turn a courtesy light switch on and off at intervals of 1.5 seconds or less to maintain communication between the Techstream and the vehicle.
Some parts must be initialized and set when replacing or removing and installing parts.
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PROCEDURE

1.	CHECK FOR DTC

(a) Clear the DTCs.

Click here

Body Electrical > Smart Key > Clear DTCs

(b) Recheck for DTCs.

Click here

Body Electrical > Smart Key > Trouble Codes

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

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

2.	CHECK ID CODE BOX (IMMOBILIZER CODE ECU)

(a) Disconnect the G57 ID code box (immobilizer code ECU) connector.

(b) Clear the DTCs.

Click here

Body Electrical > Smart Key > Clear DTCs

Click here

Body Electrical > Smart Key > Trouble Codes

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

REPLACE ID CODE BOX (IMMOBILIZER CODE ECU)

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

(a) Disconnect the G54 certification ECU (smart key ECU assembly) connector.

(b) Disconnect the G57 ID code box (immobiliser code ECU) connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
G54-13 (LIN) - G57-2 (LIN1)	Always	Below 1 Ω
G54-13 (LIN) or G57-2 (LIN1) - Body ground	Always	10 kΩ or higher

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

REPAIR OR REPLACE HARNESS OR CONNECTOR