Well, it wasn't a total mistake.

 

my security light is on and i've been told its the problem and its the reason the suburban won't start.but no-1 knows how to fix it

 

Interesting. I have an 2000 suburban, never had a security issue with it, even with hardware store keys. The security light is something that won't let it start. two things (this is a passkey something security) is with the key in ignition on, let it set for a few minutes. Has the battery or anything electrical been done recently? You might also see if there is an check engine light. If there is not, get it scanned as some abs, security, and other high end codes might not show without a high end scanner. Other thing is perhaps disconnect BOTH battery cables for about a half hour to see if that clears it.