Toyota Venza: Communication Malfunction between ECUs Connected by LIN (B2785)

Toyota Venza Service Manual / Networking / Lin Communication System / Communication Malfunction between ECUs Connected by LIN (B2785)

DESCRIPTION

This DTC is stored when LIN communication from the certification ECU stops for a certain amount of time.

DTC No.	DTC Detection Condition	Trouble Area
B2785	Errors in LIN communication between the ECUs or an open or short in communication lines. LIN communication from the certification ECU (smart key ECU assembly) stops for a certain amount of time or more.	Certification ECU (Smart key ECU assembly) Power source control ECU (Power management control computer assembly) Steering lock ECU (Steering lock actuator assembly) Wire harness or connector

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

If the certification ECU (smart key ECU assembly) is replaced, register the key.
If the steering lock ECU (steering lock actuator assembly) is replaced, register the ECU code.
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.

PROCEDURE

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

(a) Disconnect the D25, D43 and D17 ECU connectors.

Text in Illustration

Front view of wire harness connector

(to Certification ECU (Smart Key ECU Assembly))

Front view of wire harness connector

(to Power Management Control ECU)

Front view of wire harness connector

(to Steering Lock ECU (Steering Lock Actuator Assembly))

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
D25-29 (LIN) - D17-5 (LIN)	Always	Below 1 Ω
D25-29 (LIN) - D43-24 (LIN2)	Always	Below 1 Ω
D25-29 (LIN) - Body ground	Always	10 kΩ or higher

Standard Voltage:

Tester Connection	Condition	Specified Condition
D25-29 (LIN) - Body ground	Always	Below 1 V

REPAIR OR REPLACE HARNESS OR CONNECTOR

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

(a) Reconnect the D25 and D43 ECU connectors.

(b) Clear the DTC (See page ).

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

REPLACE STEERING LOCK ECU (STEERING LOCK ACTUATOR ASSEMBLY)

3.	CHECK DTC OUTPUT (POWER MANAGEMENT CONTROL ECU)

(a) Reconnect the D17 ECU connector.

(b) Disconnect the D43 ECU connector.

(d) Recheck for DTCs.

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

REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

REPLACE POWER MANAGEMENT CONTROL ECU

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