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

DESCRIPTION

Detection Item

Symptom

Trouble Area

Headlight ECU RH Communication Stop Mode

Any of the following conditions are met:

Communication stop for "HL AutoLeveling/AFS/AHS (Sub)" is indicated on the "Communication Bus Check" screen of the Techstream.
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Communication stop history for "HL AutoLeveling/AFS/AHS (Sub)" is indicated on the "Communication Bus Check (Detail)" screen of the Techstream. (The Lost Communication Time value for "HL AutoLeveling/AFS/AHS (Sub)" is 6 or more.)
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Communication system DTCs (DTCs that start with U) that correspond to "Headlight ECU RH Communication Stop Mode" in "DTC Combination Table" are output.
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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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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

1.	CHECK FOR OPEN IN CAN BUS LINES (HEADLIGHT ECU SUB-ASSEMBLY RH BRANCH LINE)

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

(b) Disconnect the A9 headlight ECU sub-assembly RH connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
A9-24 (CANH) - A9-23 (CANL)	Cable disconnected from negative (-) auxiliary battery terminal	54 to 69 Ω

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

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

2.	CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
A9-12 (GND) - Body ground	Cable disconnected from negative (-) auxiliary battery terminal	Below 1 Ω

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

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
A9-4 (IG) - Body ground	Power switch on (IG)	11 to 14 V

REPLACE HEADLIGHT ECU SUB-ASSEMBLY RH

REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER SOURCE CIRCUIT)

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual > Dynamic Radar Cruise Control System(for Hv Model): Cruise Control Input Processor (P160700)
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Toyota Avalon (XX50) 2019-2022 Owners Manual