Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Check Bus 2 Line for Short to +B

DESCRIPTION

There may be a short circuit between one of the CAN bus lines and +B when there is no resistance between terminal 18 (CA4H) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3, or terminal 17 (CA4L) of the central gateway ECU (network gateway ECU) and terminal 16 (BAT) of the DLC3.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

NOTICE:

• Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output.

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• Before measuring the resistance of the CAN bus, turn the engine switch off and leave the vehicle for 1 minute or more without operating the key or any switches, or opening or closing the doors. After that, disconnect the cable from the negative (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
• After turning the engine switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work.

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• After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.

  DTC check procedure: Turn the engine switch on (IG) and wait for 1 minute or more. Then operate the suspected malfunctioning system and drive the vehicle at 60 km/h (37 mph) or more for 5 minutes or more.

• After the repair, perform the CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed as normal.

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HINT:

• Before disconnecting related connectors for inspection, push in on each connector body to check that the connector is not loose or disconnected.
• When a connector is disconnected, check that the terminals and connector body are not cracked, deformed or corroded.

PROCEDURE

(a) Disconnect the cable from the negative (-) battery terminal.

(b) Disconnect the A49 No. 2 CAN junction connector.

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

Standard Resistance:

A

REPLACE NO. 2 CAN JUNCTION CONNECTOR

C

GO TO STEP 3

B

(a) Disconnect the A18 ECM connector.

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

Standard Resistance:

A

REPLACE ECM

B

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 2 CAN JUNCTION CONNECTOR - ECM)

(a) Disconnect the G96 No. 4 CAN junction connector.

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

Standard Resistance:

NG

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 4 CAN JUNCTION CONNECTOR - NO. 2 CAN JUNCTION CONNECTOR)

OK

(a) Disconnect the G95 No. 4 CAN junction connector.

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

Standard Resistance:

OK

REPLACE NO. 4 CAN JUNCTION CONNECTOR

NG

(a) Disconnect the G52 central gateway ECU (network gateway ECU) connector.

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

Standard Resistance:

OK

REPLACE CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU)

NG

REPAIR OR REPLACE CAN MAIN BUS LINE OR CONNECTOR (NO. 4 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))