Why does Vehicle Security light on 2009 Dodge Caliber keep coming on?

Posted: 01 Nov 2013 06:05 AM PDT

The security light is solid, not blinking. I do not have a key fob, so I'm not arming or disarming the security system. It is not doing it all the time, just every few days. Also, when it comes on the low tire pressure light comes on. I've checked the tire pressure and all tires are ok.