Can you disable the horn entirely without affecting other functions?

Why would you not want to have a horn? That's insane! Have you ever driven without a horn? Back in High School in the 80's I had a broken horn in the car I was driving... It almost got me killed multiple times.

I remember one time I got behind a giant UPS truck on a steep hill and he was lost and couldn't see me in his mirrors and started backing up really fast and I didn't have a horn so I started screaming and he didn't hear me. Finally he stopped and I started to get out of my car to let him know I was there and he started backing up again and I had to jump in and floor it again. Almost lost the whole front end of the car and it was my sister's car not mine.

There's so many moments when driving around idiots that you will die if you don't have a horn!

 

You should probably fix your alarm and/or put a camera on your car.

Your alarm could be going-off, because someone is testing it to see if they can steal your CAT. If the alarm goes off; they just keep walking - otherwise they jack it up and your CAT and sensor is gone....

Just saying........

PS. The answer to your question is unplug both horns behind your grill.....

 

In the short term, just disconnect the 12v battery at night... You could even wire in a simple switch on the negative terminal wire. But in the long run you have to figure out why this is happening. It could be the button on your key fob malfunctioning and putting the fobs in a metal box or far enough away from the car could diagnose it. Or it could be some prankster that's messing with you?

 

There's no motion sensor in Gen2 alarm... In my 2007 it's not really even an alarm, just a panic button on the FOB. which is why I suggested making sure your FOB can't talk to your car at night.

 

There is a built in alarm system which can be enabled or disabled using Techstream. From the factory this system does not have a tilt sensor but if the car was bought used a previous owner might have installed one. (It is wired to one of the door open lines, pulling its voltage low if it detects a tilt, just like opening the door pulls it low.) Easy enough to test; turn off the car, lock it, wait 5 minutes or so, then quickly jack up one corner of the car. Shake the car if you think a motion sensor might have been installed. The factory system only goes off if a locked door is opened (like the window was open and somebody reached in). I believe that in some countries there was an option for a broken glass sensor, but I don't recall if that was available in the US. I don't suggest smashing a window to see if there is a broken glass sensor!

 

The Autel is pretty good, but I don't think it can access the "customization" menu. That said, I don't remember seeing any option to disable the alarm (I could be wrong).

As far as your alarm going off, my first thought is that you have a glitchy latch switch - often it's the tailgate, but could be the hood or one of the doors.

You might look through BCM data and see if it has anything about alarm event trigger. Or see if one of the door - hood - tailgate ajar switches is activating when it shouldn't. Monitor the data (carefully) while driving. Does the red tailgate light on the dash ever flicker on?

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If the hatch sensor is iffy it might be going off if cats walk on the hatch. I don't think there is a hood sensor, but I might be wrong.

Try parking the car, lock it, wait a half an hour, then go and shake all the doors, hatch, and hood (just in case). Hard. If it doesn't go off then it probably isn't a problem with a door/hatch sensor.

 

I unlock mine and then press lock every time I get out.
If I press lock twice, The alarm goes off at the drop of a hat.

 

Be sure the mechanic key exists/works, unless you're leaving the vehicle unlocked.

 

Stumbled across this thread while researching horn replacements. In my Gen III Prius, I had an alarm triggering periodically and it seemed to happen only at night and typically a few nights in a row. Ended up finding the culprit to be an empty energy drink can that had the lid tightened back on and laying on the front passenger floor, specifically one of the tall Monster drinks w/ a cap on it. As temps dropped at night - it would cause the can to make a metallic ping noise which in turn was triggering the glass break sensor.

 

I was onto the same thought process for the OP, but my thought was, a door or rear hatch that was slightly damaged , or even just needing adjustment, and as the temp at night changed the door or hatch would change shape or shift slightly