I do have a motion alarm that is hardwired and is hanging below the front TV. I also have a hardwired alarm that is fused thru the back two 12V ignition panels below the drivers seat. This alarm is wired to the door and has a key fob and and a little push button and tiny red light on the left side of the dash where you can hardly see it. There is also a little red light on the outside of the coach just aft of the front door and that comes on when the alarm is hot. As I said, when ever the batteries have been disconnected and rehooked, the alarm goes off and is very diddicult to turn off. It also went off one time when a CAT tech left the key on over a couple of days and the batteries died. The wire for the alarm is black with a white stripe and is in a plastic flex conduit with several others
Maybe it is after market, but two different alarm techs have looked at it and said it was installed when the coach was built. Mebbee, it was an option on the 7390 LTC, but I haven't found any on here.