Toyota Tundra Service Manual: Taillight Circuit

Toyota Tundra Service Manual / Vehicle Interior / Lighting / Lighting System / Taillight Circuit

DESCRIPTION

The main body ECU (multiplex network body ECU) receives headlight dimmer switch information signals and illuminates the taillights, license plate lights and front side marker lights.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

PROCEDURE

1.

PERFORM ACTIVE TEST USING TECHSTREAM

(a) Using the Techstream, perform the Active Test.

Click here

Main Body

Tester Display

Test Part

Control Range

Diagnostic Note

Taillight Relay

Taillight relay (TAIL)

OFF or ON

-

OK:

Taillight relay (TAIL) operates (taillights turn on).

OK

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

NG

2.

CHECK HARNESS AND CONNECTOR (DRIVER SIDE JUNCTION BLOCK ASSEMBLY - BATTERY)

(a) Disconnect the driver side junction block assembly connector.

*a

Front view of wire harness connector

(to Driver Side Junction Block Assembly)

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

3G-1 - Body ground

Always

11 to 14 V
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

3.

CHECK DRIVER SIDE JUNCTION BLOCK ASSEMBLY

(a) Remove the driver side junction block assembly.

Click here

*a

Component without harness connected

(Driver Side Junction Block Assembly)

-

-

(b) Remove the main body ECU (multiplex network body ECU) from the driver side junction block assembly.

Click here

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

Standard Voltage:

Tester Connection

Condition

Specified Condition

3H-32 - Battery negative (-) terminal

Battery voltage applied between terminals 3G-1 and A-14 (TRLY)

11 to 14 V

Battery voltage not applied between terminals 3G-1 and A-14 (TRLY)

Below 1 V
OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPLACE DRIVER SIDE JUNCTION BLOCK ASSEMBLY

    System Diagram

    Terminals Of Ecu

    See More:

    Toyota Tundra Service Manual > Exhaust Pipe: Installation
    INSTALLATION CAUTION / NOTICE / HINT HINT: If an exhaust gas leak has been repaired, perform an inspection following the repair (See page ). PROCEDURE 1. INSTALL AIR FUEL RATIO SENSOR (for Bank 1 Sensor 1) 2. INSTALL FRONT NO. 2 EXHAUST PIPE ASSEMBLY (a) Connect the front No. 2 exhaust pipe assembly ...

    Toyota Tundra Owners Manual

    Toyota Tundra Service Manual

    © 2025 Copyright www.ttundra.com
    0.0103