Security problems

My stock security alarm in 97 eclipse just starts going off. Could go off a couple times a day. No ones around it, just parked. Or it could be a couple weeks and then it well just go off again. I went to a junk yard and they told me there wasn't a separte security system in that that year it was in the computer, Is this true and were would it be located. I have a 97 gst turbo, auto, 2.0 fwd. Thank you Tammy