Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Check Bus 2 Lines for Short Circuit

DESCRIPTION

There may be a short circuit between the CAN main bus lines and/or CAN branch lines when the resistance between terminals 18 (CA4H) and 17 (CA4L) of the central gateway ECU (network gateway ECU) is below 54 Ω.

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 LINES 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 LINES 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 LINES OR CONNECTOR (NO. 4 CAN JUNCTION CONNECTOR - CENTRAL GATEWAY ECU (NETWORK GATEWAY ECU))