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

GO TO HORN SYSTEM

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

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

REPLACE DRIVER SIDE JUNCTION BLOCK ASSEMBLY

Glass Breakage Sensor ECU Circuit

How To Proceed With Troubleshooting

See More:

Toyota Tundra Owners Manual > Steps to take in an emergency: If the vehicle becomes stuck
Carry out the following procedures if the tires spin or the vehicle becomes stuck in mud, dirt or snow: 1. Stop the engine. Set the parking brake and shift the shift lever to P. 2. Remove the mud, snow or sand from around the rear wheels. 3. Place wood, stones or some other material to help provide ...