I am sure someone is going to ask what year and model. My '07 SE went off in a parking lot, I didn't realize it was mine. Never heard it before. Mine has the VIP RS3200 + Alarm.
Only if you have the option. It's standard on the Limited, optional on the SR5 and Sport Edition. On mine, it honks and lights flash only when the doors are opened without the key or remote. There's no shock or impact sensor from the factory. There's an accessory glass breakage sensor for it.
You can test for it by rolling down a window and lock the 4Runner as your normally would. Wait a minute or so, then reach in through window, unlock the door and open it. The horn will honk and lights will flash if you have the alarm option.
Yeah, I installed the RS3200 myself. It was mildly easy. The shock sensor would be really nice, but I like having the stock key fob. Just out of curiosity, did you have naything valuable in your truck, aftermarket HU, or subs? Anything like that?