Toyota Tundra Service Manual: Horn Circuit

Toyota Tundra Service Manual / Vehicle Interior / Theft Deterrent / Theft Deterrent System / Horn Circuit

DESCRIPTION

When the theft deterrent system is switched from the armed state to the alarm sounding state, the main body ECU (multiplex network body ECU) transmits a signal to cause the horn to sound at intervals of 0.4 seconds.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

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

PROCEDURE

1.

CHECK HORNS OPERATION

(a) Press the horn switch and check if the horns sound.

Result

Result

Proceed to

Horns sound

A

Horns do not sound

B
B

GO TO HORN SYSTEM

A

2.

INSPECT DRIVER SIDE JUNCTION BLOCK ASSEMBLY

(a) Remove the driver side junction block assembly.

Click here

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

3H-27 - A-28 (HORN)

Always

Below 1 Ω
OK

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

NG

REPLACE DRIVER SIDE JUNCTION BLOCK ASSEMBLY

    Glass Breakage Sensor ECU Circuit

    How To Proceed With Troubleshooting

    See More:

    Toyota Tundra Service Manual > Intuitive Parking Assist System: Precaution
    PRECAUTION 1. PRECAUTION FOR INTUITIVE PARKING ASSIST SYSTEM HINT: In very cold weather where a malfunction display appears, the sensor may not detect obstacles. If the malfunction display appears, visually check the sensor first. If the sensor is free of foreign matter but the malfunction display r ...

    Toyota Tundra Owners Manual

    Toyota Tundra Service Manual

    © 2026 Copyright www.ttundra.com
    0.0198