Is anyone familiar with the security system that was stock on a 1984 C4.

 

don't know if you've fixed it ye but sometime disconnecting and reconnecting the security module under the dash works. Never tried it in a Vette but worked in a chev 3500 van.

 

Just for kicks... My '84 has a problem with the driver's side door lock not properly deactivating the security system. When I have had this problem, using the door key in the passenger's side to lock and unlock the door cleared the security system and allowed me to start the car.

FYI for the rest, the '84 does not have a chip encoded key, it just uses the old metal key blanks. The security system is activated and deactivated by the door locks. The one "goofy" thing is that having the proper ignition key doesn't clear an alarm in the security system

Dave

 

Sounds like the system has lost the memory of your key. I had the same problem on on Olds awhile back. The fix was to turn the key to the start position then release it. Leave it in the run position for 10 mins so the system can relearn your key (no chip). After 10 mins turn the key to the off position then try to start it again.

Hope this helps.