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.
how to change a valve cover gasket on a 97 mercury grand marquis ?
how to remove right turn signal relay on 1986 mercury grand marquis
connected to the turn signal
NO belt in the 302cid engine of a 1988 Mercury Grand Marquis. it is a chain with gears
On a 1996 Mercury Grand Marquis the windshield washer squirter button is on the end of the turn signal lever
Mercury Grand Marquis was created in 1983.
Take to old one out and put the new one in. Access from inside the trunk.
Under dash, driver's side.
Replace the flasher relay if none of them are working.
( 5 quarts with filter change ) according to the 1999 Mercury Grand Marquis owners manual
( 6 quarts with engine oil filter change ) according to the 2003 Mercury Grand Marquis Owner Guide
how to replace starter on 2000 mercury grand marquis