Most likely its a fuse or a burnt out bulb.
If it ends up being a burnt out bulb, see sources and related links below for bulb information.
How do you turn on dash lights 1993 mercury grand marquis
where is the fuse for tail lights in 1988 mercury grand marquis
walmart blinkers christmas lights buy where?
Turn on headlights/parking lights and adjust dimmer control
so what do i do if my blinkers do not when the lights are on
where you turn on the headlights ... push the button
Probably a bad front wheel bearing/hub assembly with the abs sensor in it
It is a module under the dash.
dash lights and tail lights cut out
There is a lights control box under your steering wheel.
Mercury Grand Marquis for one and I am sure there are others that I am not familiar with
change the brake lights check the fuse check the brake light swtch