how u diagnois Anti Theft if Key Trick didnt work?

[comet240]

hi i have this 97 cav and before i have to take it to the GM dealer for them to scan it or diagnos it is there a trick to figure out whats not working on the car?

as i done the 3 10 min key trick didnt work even swaped out from my 97 sunfire the key cylinder and did the 3 10 min key trick and still didnt work

what else can i try that can test to narrow it down

[autojoe]

when you turn key to on position does the security light steady and go out or flash?starter turn over/start and stall?more info?what size engine?

[comet240]

the light never goes out never flashes

orginally what happened was i replaced the whole exhaust and the cat was turning red hot replaced it it was turning red hot got told later probably the temperature prob telling car its too cold and putting more raw fuel in but by then was too late the car was idling for an hour then came back it was shut off and could never start it again kept turning it over and over and over and then noticed later theft mode was on

it can start and stall if u prime enoguh times the engine as u can turn key on and off and hear the pump running and if u spray carb cleaner in the intake u can keep car running its a 2.2 engine and my mother told me from GM they told her also if battery is disconnected for a certain amount of time it engages theft mode and the only cure is GM they have to reprgram the whole system like what kinda system is this crap?

as i dont have the battery in the car now i even bought a 200 dollar bypass from newrockers that didnt work for it