usually a broken wire causing a dead short(grounding out to the cars body on a power wire)
remove the rear tail light housings and check to make sure that one of the wires is not crimped by the housing (this happens alot on these cars if it simple repair the wire and make sure not to crimp it when re installing the housing if it's not at the housing you'll need to check the wire all the way from the front to the back (this requires removing the seats and the carpet ) your looking for any spots that are showing bare wire and in some cases flat spots on the wire (it's a common problem because the wiring harness doesn't clear the tail lamp assembly when changing blown bulbs and more often then not the wires get crimped
Burned out bulb?
I have a 1998 ford grand Marquis- and the problem is the air suspension light stays on- how to fix this problem
Have the codes read.
check your fuses
Why ? Just replace it.
Fuse, loose connection, or the light switch. how do you remove the dashboard on a 94 mercury grand marque?
You won't know until you get the code read.
where dose daytime running lamp module go on92 mercury grand marquis need to replace one
where is the running light sensor on a 2003 grand marque
check the bottom of the steering column
assuming you mean the light bulbs, see the answer to "how do you change turn signal lamps both front and rear on a 96 mercury grand marquis" right here in WikiAnswers.
Sounds like receiver ok, check the speakers/fuses.