What is the story with the LX 450's alarm? It constantly goes off when I leave the truck and come back and open one of the doors. I am not arming it, is there a way to prevent this from happening? Also my alarm does not "chirp" when arming and disarming. I read in another thread that the device is located on the dirivers side fender but I was unable to locate it. Can anyone give me a better description of the device and tell me how much it would cast to replace? Thanks for you time.