So after lunch today i went to start my car (96 Z28) and the security was on. it wouldnt start. the light wouldnt go away. why would this happen?

 

Your resistor in your key is not getting detected by your system. Is it flashing?

 

Could be several things. Take a look at this link. Usually the key going bad or the key cylinder.

http://shbox.com/1/pass_key.html

 

I had the same problem and it was the tiny white wire that goes to the lock cylinder that broke. I took the column apart and tried to solder the wire back together but it kept on breaking.
If you come across the same issue I would recommend wither buying a new lock cylinder and having the car reprogrammed to that key. Or use a multi meter to measure the resistance in the key then go to radio shack and buy a resistor or series of resistors to match that resistance. Then simply wire the resistors into the connector under the dash. Car will start every time.

 

or have the vats turned off at the same time have a tune done.