1995 Lincoln Continental

I have a 1995 Lincoln Continental with 126,000 miles and a V-8. It tells me that one of my rear doors is open when I know that they are not. I have checked both doors and they are closed. There is no black button on the frame for the door to push in when it is closed. The interior lights stay on and my doors wont lock when it is saying door ajar. And then sometimes all of the sudden it will just shut off and go away. Could it be a relay sticking somewhere or possibly a limit switch of some sort going bad, and most importantly where would it be located? Any and all help is greatly appreciated. Thanks alot!