99 yukon denali, 750 autopage alarm

ok here is the deal i have a 99 yukon denali like mentioned above, it has a 750 autopage alarm, all of a sudden the truck did not want to start, so icalled some guy over to check it out. he replaced the relay of the alarm 3 times due to the same problem all them 3 times in 1 day because once it would turn off it would not turn back on. ok now the guy tells me that it is the switch i dont know if its the ignition switch or the key switch what i do know is that he said the "switch" sometimes sends a positive signal and sometimes a negative. well it wasnt turning on so what he did is he brought out the cables underneath the dash and he opened the key of the ignition and he got a ground wire and connected to a yellow wire and it turned on...ok then i went home turned it off and it did not turn on n e more, another thing that i noticed the day before the problem started, is that on dash where odometer is at the shift selector the one that tells u if ur in p,n,r,d,1,2 u know, well that little orange light would come off after a while of driving or some times it would just be off, ok what i also have noticed is if that lil light is on when i open the key then the truck is going to turn on, and if its not on then its not going to turn on. so that is my big problem and then i called autozone to see how much the swithch was and they tell me the truck only has an ignition switch so ???? i also have checked all the fuses they seem okay.... PLEASE HELP!!!! THIS IS A BIG PROBLEM FOR ME!!!! THANX IN ADVANCCE 

sound like a passlock 2 problem. its gm's way of keeping someone from hot wireing your car  a remote start is no more than hotwireing a car. now there are many interfaces thay aid installers in gitting around this thats what it sounds like he replaced 3 times. some good advise, the paslock system in your truck is very simple for some one that knows what their doing take your truck to some one else . bring back the rotary phone so i dont have to press 1 to proceed in english

so i tell them its the passlock system?, it sounds about right because whenever it is turned on the security light remains on, only sometimes though..