Hello... joined to find out why my horn won't stop blarring :o

I have a 2006 double cab tundra with ~195K on it. Horn started blaring last week while parked in driveway. Couldn't get doors unlocked with aftermarket security system, but its been working for over a decade. Had to use manual key to enter and then in a panicked ignorant attempt to stop the blaring I grabbed the wire cutters and cut wire to horn. It still drives fine, brakes, turn signals and and 4 ways work. Only issue is the now not working horn, and the doors not responding the key fob (even though the security system responds to it)

There is already a March '20 thread about this horn issue (below) but no shared solution as of yet... messaged the OP... hoping i can find answers. There is a thread for the second gen as well, but since i already mistakenly ordered a 2nd gen part for a 1st gen, I want to avoid another embarrassing conversation with my mechanic. i'm mechanically ignorant, but if i can help diagnose the issue and get a part, i'll save $ on the repair. Thanks all, glad to be here.

https://www.tundras.com/threads/horn-honks-continuously.63244/

 

Welcome from NY.

Hopefully a 1st generation guy or a Toyota Master Technician will chime in.

 

I would swap out the horn relay first. Seems the most likely suspect. Your horn switch on the steering wheel grounds the coil to activate the horn relay, which in turn provides power to the horns. There should be several single pole single throw relays in the truck that you can use to test. Something like the taillight relay would work. I think it should be marked "TAIL." Pull that relay and plug it in to the horn relay position and see what happens ..... or what doesn't happen.

 

Welcome aboard from SoCal.

 

Would that theory still hold true since the door locks are also on the fritz? Key fob turns on/off security (but no longer doors), switch inside for door locks still works.

 

Welcome from Pennsylvania

 

I think it might still hold true. The aftermarket alarm might be tied into you horn circuit, and would blow the horn when someone tried to break in, disabling the remote door locks. But then, it might be the alarm system itself that is causing your problem of the horn activated all the time. Both scenarios are possible. You can only try to eliminate one at a time. Try the relay.

 

Welcome from LA (Lower Alabama)!

 

Welcome

 

welcome from So Cal

 

Welcome from Ohio

 

won't stop blarring



BWAAAAAHAHAHA!! Tears spewing from eyes!

 

Welcome from NC!

 

If it were me I would remove the after market alarm entirely. As they age those seem to be nothing but problematic anyway.

As a side note that is not helpful to this problem at all, this reminds me of my friends 79 chevy in high school lol it was a beat ass truck and the horn would go off at random while he was driving. The driver door would also fly open on right hand turns but stopped doing so one day after it slammed shut from doing that. After that it no longer opened and everyone had to go in through the passenger side. Good times lol