Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: High Beam Headlight Circuit

Toyota Avalon (XX50) 2019-2022 Service & Repair Manual / Vehicle Exterior / Lighting (ext) / Lighting System(for Hv Model Without Cornering Light) / High Beam Headlight Circuit

DESCRIPTION

The main body ECU (multiplex network body ECU) controls the high beam headlights.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

Inspect the fuses for circuits related to this system before performing the following procedure.
Check the operation of the low beam headlights. If the low beam headlights do not operate normally, refer to Problem Symptoms Table.
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Before replacing the main body ECU (multiplex network body ECU), refer to Registration.
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PROCEDURE

1.	PERFORM ACTIVE TEST USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(d) Enter the following menus: Body Electrical / Main Body / Active Test.

(e) Perform the Active Test according to the display on the Techstream.

Body Electrical > Main Body > Active Test

Tester Display	Measurement Item	Control Range	Diagnostic Note
Head Light Hi	High beam headlights	OFF or ON	-

Body Electrical > Main Body > Active Test

Tester Display
Head Light Hi

OK:

High beam headlights illuminate.

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

2.	INSPECT DIM RELAY

(a) Inspect the DIM relay.

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REPLACE DIM RELAY

3.	CHECK HARNESS AND CONNECTOR (POWER SOURCE - DIM RELAY)

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

Standard Voltage:

Tester Connection	Condition	Specified Condition
1 (DIM relay) - Body ground	Power switch off	11 to 14 V
3 (DIM relay) - Body ground	Power switch off	11 to 14 V

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.	CHECK HARNESS AND CONNECTOR (DIM RELAY - MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU))

(a) Disconnect the G33 main body ECU (multiplex network body ECU) connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
2 (DIM relay) - G33-13 (DIM)	Always	Below 1 Ω
2 (DIM relay) or G33-13 (DIM) - Body ground	Always	10 kΩ or higher

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

REPAIR OR REPLACE HARNESS OR CONNECTOR

Headlight Dimmer Switch Circuit

How To Proceed With Troubleshooting

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