S 10 / Blazer starting problem

Had to knock out ignition -- trying to hot wire start. engine comes up runs for 2 sec and stops -- every 5 or 10 or 15th attempt will continue running flawlessly until shut down and attempt to restart

What year and model? If it has it, it sounds like the Passlock security system is doing its job. Does the security light on the dash come on?

it is a 1999 s10 4cylinder, and yes security light is on....Do you know where the security relay is located....That is what I was thinking it was, but don't know where it is...Thankyou