Brake light and turn signal and wire location

I have a 1995 Oldsmobile cutless
surpreme sl and my brake lights dont
work when i brake also the turn signals
or hazards dont either.at first the
signals workd then just the left did.i
checked and changed
bulbs,fuses,flasher relay but i think is a
loose switch wire either under the hood
or by the brake how would i identify
which wire or switch is which and their
location