I have a 2000 Grand Marquis the overhead lights deep going on when the car is turned off, resulting in the battery going dead. If I take the light out (also the ones by the floor) will that take care

get a NEW battery...clean the spot where the 1/0 cable connects to your chassis/ground...must be able to pull 300 cold cranking amps at least~ here and to the engine block (near the alternator) as well~

when you maintain the main ground connection any latent charge should dissipate (LCM, BCM, ECM...all)~

No, thats not the problem.

what's NOT the problem LindaL...http://www.youtube.com/watch? feature=player_detailpage&v=zdIKNnwEjIs

full disconnection of all things electrical did not reset this condition? is this what you are so rudely trying to tell me there?

It very well could be an LCM. The very best way to tell if it's an expensive Lighting Control Module is to hook up a scan tool that is capable of reading the LCM's inputs and outputs. You could try pulling all the bulbs - but that's not a cure and you could have other failures looming inside the LCM on top of that. There are other things that can bring a battery down: (Like judge_roy enjoys frequently pointing out) failing batteries and connections that fail, Alternators that keep the field energized after the car has shut off, fuel pumps that run incessantly etc. A couple of interior light bulbs should not bring a battery down overnight. Ever. Either the Battery isn't holding a charge OR the battery isn't being charged enough. I work on a Fleet of Crown Victoria Police Interceptors (same car - different badge). Frequently we see Alternators that stay on, AC clutches that stay on, Batteries that are WAY overtaxed by being repeatedly discharged and recharged (cop cars do that a lot). A typical LCM failure though usually involves the Headlights flashing on their own - not the interior lights. BTW - is the vehicle equipped with an aftermarket alarm?

The problem with the lights cycling on and off by themselves may be due to the keypad in the drivers door if you have that feature. I have both a 2000 Crown Vic and a 2004 Grand Marquis that had that problem. I solved that by disconnecting the keypad. Unfortunatley now the Grand Marquis has a bad door position switch or a short that is keeping the dome light on constantly so more electrical fun is in my future.

I have a 1999 grand marquis with the same issue. The dome light will come on intermittently while the car is off. Most the time it would stay on. Sometimes shutting off but mostly staying on. I just removed the fuse. But by doing that my clock and door locks wont work. The doors can still be locked and unlocked using remote. This is no cure but it will stop the battery from draining. Im not sure if the keypad on the door still would work as mine stopped working several years ago. Its nice having a dome light, clock, and being able to lock doors without the remote but for me its not a huge deal. Check owners manual for proper fuse. I thinks there is a short or something with the dome wiring sometimes tapping it would make it go out but Id never know if it would stay off all night. A new battery should be drained overnight just from dome so replacing that might be a good idea as well