My Gen 2 TL factory alarm system will go off every time after midnight when there is super light rain it went off 3 times at the point that I got so mad I dented the car and I took a wrench out and unplug that battery.
Where is that factory alarm system module located to detect vibrations or what not.
I check my cameras outside at that time and no one's around the car and no one's running away from it.

 

My '00 factory alarm only senses the door, hood and truck opening. No shock sensors. It's common, after all of these years, for one of these sensors to malfunction intermittently . For me, it was the hood sensor. I just disconnected it and didn't bother replacing it. I would be home and my alarm would just randomly go off at night inside my garage.

Are you sure your factory alarm has shock sensors? Perhaps the rain was just a coincidence.

The hood, trunk and driver's door sensors probably malfunction the most. Trunk and driver's door because of heavy use, hood because of all the gunk and dirt. Disconnect all three and see if the problem stops for a while, then connect them one at a time until you find the bad sensor.

 

Maybe some anger management would be helpful.