Alarm just goes off

double posted. wow.
when it beeped, did you look in the display (RPM)
it tells you why?? the VFD or EVIC tells you why.? (rpm dial)
do you park with the alarm on , on the street or a garage?????
if in a garage park and turn alarm off. it does turn off the alarm.
did you bump the panic button?
eg its under your pillow?? LOL or the cat chewed it?
read your other post, it's got lots of answer there.
to find cause.
if the horns stays off, if alarm is off then its not the horn button.

as many will say. there are 4 things that run the horn.
button horn
alarm
door locks.
panic.(part of alarm but not totally)
on my car, i have most themn turned off, like the lamp flashings.
and the horn chirp is off on all my cars, all i get is the door lock click sounds, nice (neighbor friendly)
so turn all all that and see if the horn still fails.

that panic button can fail,
if mind did id pull the fob battery and then use FOB 2.
to see of the FOB fails.

your other post said driving
this one says, parked. 3am clue.

I have a 2004 Lincoln LS,disconnect the negative battery for 10 minutes,then connect cable back,when you open driver side door alarm will go off,insert key in ignition and alarm will go off.Get in car,lock all doors and windows,turn key to the right 8 times quickly,then doors will unlock,then quickly push any button on key fob.

possible -but all these fancy electronics are beyond the realms of most people and you need the factory to reset and diagnose the fault .even us mechanics have to admit defeat with faults like this and return vehicle to the dealer then charge for the time involved in taking and collecting the car ,take it straight to the dealer yourself

Depending if it is a aftermarket or a factory alarm, they should all have fuses that can be removed. By removing the fuse, you may lose your keyless entry option. Most aftermarket alarms have a siren that is usually mounted under the hood in the engine compartment area. I've seen where people have cut the wire going to the siren to disable it but keep the power going to the alarm system to keep the keyless entry still functional if it came with the alarm system.
Factory alarms usually use the existing horn for the alarm. If that is the case, you might need someone who is experienced to disable the circuit so that the horn will not sound if alarm goes off but the horn will still be functional when needed. Hope this helps.

It sound the alarm relay or the alarm module is broken. Can you find the fuse for alarm system? If you can disconnect it.
You can find the alarm module under dashboard, disconnect it. Hope it can help

The usual cause of this is the alarm switch on the bonnet panel is too low and creeps up when you leave the car .

Just put some washers behind it so its snug when the bonnets shut down - I have done a few like his and its easier than disconnecting .

Is the alarm causing the horn to honk? If so, you need to figure out what is causing the alarm to trigger, which could be any number of things.
Or, the panic module could be failing.
It is least likely to be the horn ring unless the only way you can get the horn to stop is by "beating the horn button on the steering wheel".

If it is, then you can replace the parts for the horn button, but you will need to get an assembly manual for the vehicle. Be sure to disconnect the battery before attempting to remove the airbag module. If it goes off, then you risk injury, and, they are not cheap to replace.

check a reputable alarm installer sound like your factory lock module is giving trouble

find the horn and look for a wire then cut the wire that goes to the alarm NOT THE HORN WIRE