Thanks for the replies. I just now got to get on the site to read them. Let me clarify:It's a factory system. It is apparently only an entry alarm; as far as I know there are no motion sensors or vibration sensors (according to the owner's manual, which it seems the service techs aren't allowed to read). It is armed any time the vehicle is locked, and a red light on the dash flashes. I can't find the horn or control, and I can't find anything to trace to them. The light in the dash is where I would have to dismantle the dash to get to it. The truck even has factory applied stickers on the windshield for the alarm the service manager says I don't have. All I want is for it to work correctly or be removed; I don't care which. I just don't want to go without a ride for months while the clowns in the dealer's service department try to figure out whether I have a factory-installed entry alarm, and I don't want to explain why I had to leave the truck unlocked to let the thieves have my radio, siren, and control box. Sheesh!
Do you turn the work radio off at night? The speaker vibration in your cab sets off your alarm? Could that be it?