1999 Dodge Caravan Door ajar light

I recently bought this van and it had no apparent electrical problems. Just one week after buying it, everytime I start it the door ajar light stays on even after all the doors are closed. When I shift into reverse it goes away but as soon as I put it into drive it turns back on, this also turns the interior lights on. I think its a short somewhere in the dash area but I'm not sure. Any suggestions?