Truck wont start ?

[prodigy215]

I have a 2002 GMC Denali, this morning my truck didnt start. It seem like a security issue? Usually my security light shows on dashboard after i put key in "ON" position, or when i start truck up.

 

But now the security light doesn't even Show on dashboard. What can cause this problem? My battery voltage at 12.7v. Please help thanks

[It's Tim]

Doesn't start or doesn't crank?

[prodigy215]

It cranks but it doesn't start up

 

 

Doesn't start or doesn't crank?

[prodigy215]

What can cause the Security light not to work at all? Is it a box or something that can go bad? Im wondering if it could be that