Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Headlight ECU LH Communication Stop Mode

DESCRIPTION

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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• Inspect the fuses for circuits related to this system before performing the following procedure.

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 A8 headlight ECU sub-assembly LH connector.

(c) Measure the resistance according to the value(s) in the table below. Standard Resistance: Tester Connection Condition Specified Condition A8-24 (CANH) - A8-23 (CANL) Cable disconnected from negative (-) battery terminal 54 to 69 Ω

*a Front view of wire harness connector (to Headlight ECU Sub-assembly LH)

NG

REPAIR OR REPLACE CAN BRANCH LINES OR CONNECTOR (HEADLIGHT ECU SUB-ASSEMBLY LH)

OK

(a) Measure the resistance according to the value(s) in the table below. Standard Resistance: Tester Connection Condition Specified Condition A8-12 (GND) - Body ground Cable disconnected from negative (-) battery terminal Below 1 Ω

*a Front view of wire harness connector (to Headlight ECU Sub-assembly LH)

(b) Reconnect the cable to the negative (-) battery terminal.

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

Standard Voltage:

OK

REPLACE HEADLIGHT ECU SUB-ASSEMBLY LH

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)