Re: Air Suspension - 2002 Grand Marquis
My '96 has most of the wiring for the air suspension, yet it never had air suspension. Haven't looked too closely at the fuse block though. behind the carpeting in the trunk, where the air suspension switch would be, There is a plug with a cap on it.
I think that for ease of assembly these things all got the same main wire harness and accessories were just left out during final assembly.
without the switch in the trunk and light on the dash, my guess would be that you don't have air suspension. the one way to know for sure is to look under the back and see if you've got coils or bags for springs.
1996 Mercury Grand Marquis GS ~89,000mi, Willow Green inside and out. It's very green.
1998 Chevrolet Malibu Base V6 187,000mi (sold)