Horn and maybe alarm system issue

[Longmark999]

I searched around and this problem appears to be somewhat unique. A couple of months ago I drive my 03 4Runner from Houston to upstate NY. On day 2 of the drive, while it was raining pretty heavily (not sure if that's relevant or not) I hit a reasonably significant uneven pavement seam, and my horn honked about 5 times quickly. This problem then repeated itself even with moderate bumps about 2 or 3 more times. After that, whenever I hit even a moderate bump, it was as if the alarm was going off... the horn would honk slowly for about a minute. I'm not sure if the lights were flashing and the 4 ways were flashing because I was busy making the "I have no idea what's going on" gestures to the drivers beside me. I pulled the horn fuse at the next rest stop, but I've got a state inspection coming up, so I'd like to get a fix of anyone had any ideas.

Thanks in advance

 

[riceandpho]

check the battery on the key fobs, hit the unlock button couple of times, seems like an aftermarket system was installed.