1997 Grand Marquis, why would turn signals/brake lights stop working.

I would guess it's the turn signal switch inside the steering column under steering wheel (you have to remove air bag and steering wheel to get access to it) the brake lights also go through the turn signal switch. I'll try explain if you don't understand why the brake light go through the turn signal switch. For example when you have your foot on the brake and one of turn signals on it turns off the brake light in the rear on the side the turn signal is on. Hope that makes since. Now I would GUESS the part is around 50 to hundred dollars if you purchase it yourself if you have a garage do the work they will charge you more for the part.