RankRam is right... you put the truck in park, pull the key from the ign switch, lock the door, and you are done... the engine stays running 'till it gets to the pre-set temp, then it shuts off... if the thief brakes the window while you are walking away, he can't get it out of Park, or turn the wheel... it's pretty simple setup... just wish it had some life to it... . My Isspro has no provision for any brake switch kill... Diesel Manor sells the Isspro, but if you don't buy it from them, they say on their site that they won't help you with any problems... buy one that has a good service policy. .