Why is the Security light on in a 2001 Chevy Blazer that doesn't even have a security system?

The 2001 Chevy Blazer does have an ignition security system that is controlled by the computer in the vehicle. The light might come on because of an error that is coming up in the computer due to a key problem or an ignition problem. This is a common issue with the 2000 and 2001 Blazer.