Taillight Relay Circuit [06/2018 - ]: Procedure

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PERFORM ACTIVE TEST USING TECHSTREAM

Connect the Techstream to the DLC3.
Turn the power switch on (IG).
Turn the Techstream on.
Enter the following menus: Body Electrical / Main Body / Active Test.

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
Taillight Relay	Taillight relay	OFF or ON	-

Body Electrical > Main Body > Active Test

Tester Display
Taillight Relay

Taillights illuminate.

Result

Proceed to
OK
NG

Result:

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE. Refer to PROBLEM SYMPTOMS TABLE [06/2018 - 08/2021] , or refer to PROBLEM SYMPTOMS TABLE [08/2021 - ]

Result:

See step 2

CHECK HARNESS AND CONNECTOR (POWER SOURCE - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

Disconnect the 3K instrument panel junction block assembly connector.

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

Standard Voltage

Tester Connection	Condition	Specified Condition
3K-1 - Body ground	Power switch off	11 to 14 V

Result

Proceed to
OK
NG

Result:

REPAIR OR REPLACE HARNESS OR CONNECTOR

Result:

See step 3

INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY

Component without harness connected
(Instrument Panel Junction Block Assembly)

Remove the main body ECU (multiplex network body ECU) from the instrument panel junction block assembly.
Refer to REMOVAL [06/2018 - 08/2021] , or refer to REMOVAL [08/2021 - 09/2022] , or refer to REMOVAL [09/2022 - ]
Connect a positive (+) lead from the auxiliary battery to terminal 3K-1.
Connect a negative (-) lead from the auxiliary battery to terminal MB-14 (TRLY).

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

Standard Voltage

Tester Connection	Condition	Specified Condition
3H-30 - Auxiliary battery negative (-) terminal	Always	11 to 14 V

Result

Proceed to
OK
NG

Result:

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU). Refer to REMOVAL [06/2018 - 08/2021] , or refer to REMOVAL [08/2021 - 09/2022] , or refer to REMOVAL [09/2022 - ]

Result:

REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY. Refer to REMOVAL [06/2018 - 08/2021] , or refer to REMOVAL [08/2021 - 09/2022] , or refer to REMOVAL [09/2022 - ]