Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Check Bus 3 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 6 (CA3H) and 21 (CA3L) 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 power 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 (-) auxiliary battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
• After turning the power switch off, waiting time may be required before disconnecting the cable from the negative (-) auxiliary battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) auxiliary 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 power 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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• Before replacing the DCM (telematics transceiver), refer to Registration.

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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 (-) auxiliary battery terminal.

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

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

Standard Resistance:

B

GO TO STEP 3

C

GO TO STEP 4

A

(a) Disconnect the G96 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

GO TO STEP 4

(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))

(a) Reconnect all wire harness connectors.

(b) Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the short circuited branch line is connected.

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(c) Measure the resistance according to the value(s) in the table below. Standard Resistance: Tester Connection Condition Specified Condition G52-6 (CA3H) - G52-21 (CA3L) Cable disconnected from negative (-) auxiliary battery terminal 54 to 69 Ω HINT: If the resistance becomes normal (between 54 and 69 Ω) when the connector is disconnected from the ECU or sensor, there may be a short in the ECU or sensor. If the resistance does not become normal when the connector is disconnected from the ECU or sensor, check for a short in the wire harness and repair or replace the wire harness or connector if necessary.

*a Component with harness connected (Central Gateway ECU (Network Gateway ECU))

OK

REPLACE ECU OR SENSOR

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR