if it is blinking steadily without your input , button on the end of the gear shifter, then you have an internal transmission problem, or a pcm problem. Neither of which are cheap to fix.
what will fix the overdrive light from flashing in a 1996 mercury grand marquis its a gear ratio problem between 1 and 2 shift
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.
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.
Have vehicle scanned to determine the problem
The repair section on autozone.com explains how to change the light switch.