I just bought a 2004 Grand Marquis GS and the prior owner had the dealer disable the remote entry system. They claim the dealer unplugged something in the trunk that disabled it. The book shows a 4 button remote with a trunk release, but we received a remote with only 3 buttons (lock, unlock, & panic). Does anyone have an idea what and where the plug may be that disabled the remote entry system? And, how do we get the 4 button remote, and what must we do to get it to work with our car?

Thanks for any help! ;)

Do you mean a Remote Start system or a remote entry? The key fob you have is the factory system with lock, unlock & panic, which is a 3 button fob. I have a remote start system in my 04 Sport, which was installed by Ford, & it has the 4 button, lock, unlock, panic & start. There are no connections in the trunk regarding the lock or unlock system. The remote start system has a small antenna. A Ford/Mercury dealer can tell by looking under the dash if the car had a remote start system. Hope this is of some help.