When we purchased our 2001 38fdds in 2001 the dealer installed an alarm on the Coach and put in a door switch for the alarm. The door switch was drilled into the door frame like the switch for the stair step. I have only used the alarm a couple of times depending where it is parked.
Since we have a dog we do not set the alarm and we do not lock the door in a campground because we are worried that in an emergency no one will be able to let the dog out.
We do lock the door in parking lots with the dog inside and we go into a store and we do not set the alarm.