Venture PK3 Secuity Light

MY 2003 Venture "Secuity Light" comes on after I start the car. Sometimes it goes out, and one time it came on when I pushed the criuse control botton. Just out of warranty. I don't have starting issues, but I'm concerned I might have some in the future if I don't do something to fix the problem. Any advise is appreciated. Don't really want to go to the dealer for obvious reasons...$$$$