I have a 2003 Mercury Mountaineer. The interior lights come on and stay on after you turn off the vehicle. I've searched many forums and have seen people that say to spray the door latches, so I did that and still have the issue. Also saw someone post about the door ajar display. It works fine, it comes on when I open each door and goes off when I close the door. So that's suppose to eliminate a door switch problem. The only way to get the interior light to go off is to manually turn the light switch dimmer all the way down and click into the off position. So I have seen a post about a possible GEM (Generic Electronic Module) problem that could be causing this. I have one other strange behavior that leads me to believe its something like the GEM. Each time I hit the rear window defrost button, the interior light comes on, a bell sounds and the door ajar light comes on. I read that if you change out the GEM you have to upload the configuration to a scan device first. Is that the case? So do I have to go to a dealer and pay several hundred dollars to fix a light problem? Any help is very much appreciated! Thanks!