What causes it to stay on?

 

vats is not happy. could be key contacts are dirty, maybe the contacts in the coluum. try spraying electrical cleaner in there and clean the key contacts. see if that helps

 

Yep that has worked for me.

 

It's not affecting the car at all. It's been on last 2 days. I have new key and ignition switch but I've had them over a yr and this is first time light has been on.

 

When the security lamp is on and the engine is still runs it means that VATS has been disabled. A VATS problem has occurred while the engine was running, so the software concluded that the car was not being stolen, and therefore the VATS itself was in trouble. When this condition occurs the PCM ignores VATS.