Check the fuse first then the brake light switch
you remove plastic red/white cover with 2 screws and remove bulbs.
you dont go to the dealer who will charge you 50.00 for replacing a 5.00 part that takes 2 minutes!
Under the dash near the brake pedal lever.
D.O.T. ( 3 ) brake fluid ( meeting Ford specification ESA-M6C25-A )
lower the tail gate and look in tail gate jam. bolts are where the cables that hold tail gate are anchored
Inside bumper back of it
Check the operation and alignment of the brake light switch, located at the upper end of the brake pedal under the dash area
To replace the tail light bulb, open the tailgate and on the inside there is two little bolts. Take those out and the tail light should slide out, just turn the bulb holder and it comes out.
You want a violent twitch for your 1997 Ford F150?