Replacing it is simple. I've never had to actually do it as they rarely fail, but it's plug-and-play with no programming needed.
You don't have to go through Ford to get a replacement. Dorman and other aftermarket companies have them.
'03 Mercury Marauder (The Blackbird)
Trilogy Motorsports supercharged #61
Too many mods to list / Driveway Queen
'04 Grand Marquis LS Limited Edition (Spruce Green)
Daily Driver (Thanks, Adam!)
'00 Grand Marquis GS (Silver)
Rotted frame and broken transmission crossmember