2000 Blazer starts for 2 seconds then dies
 

I have a 2000 blazer that was runing fine until I replaced the ignition and the ignition case, now the key turns, the truck starts, then dies. There is no security light that blinks or stays on, it comes on only at the when I start the truck, then goes right off? Some one please help! Thanks

Immobilizer antitheft control. YOu are going to have to look up fixes for GM Pass Key III Anti theft system to find the cure for this. The light comes on because the PCM doesnt recognize the key or the ignition switch.