Toyota Avalon (XX50) 2019-2022 Service & Repair Manual: Taillight Relay Circuit

DESCRIPTION

The main body ECU (multiplex network body ECU) controls the operation of the TAIL relay.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

• Inspect the fuses for circuits related to this system before performing the following procedure.
• Before replacing the main body ECU (multiplex network body ECU), refer to Registration.

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PROCEDURE

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

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

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

OK:

Taillights illuminate.

OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

(a) Disconnect the 4K instrument panel junction block assembly connector.

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

Standard Voltage:

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

(a) Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.

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(b) Connect a positive (+) lead from the auxiliary battery to terminal 4K-1.

(c) Connect a negative (-) lead from the auxiliary battery to terminal MB-14 (TRLY).

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

Standard Voltage:

OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY