1997 Chevrolet Cavalier signals

I'd check voltage and ground for the lower brake lites and turn signal. A lot of vehicles, the lower brake lites and turn use the same bulb filament. I'll check your wiring.

Your lower brake lites are wired through the multifunction switch. They use the same bulb filament, just not at the same time. Left side rear stop/turn, yellow wire is voltage, black wire is ground.

Right side rear stop/turn, dark green wire is voltage, black wire is ground.
You may have to check your work on that multifunction switch? You may be able to check the proper color wire coming from steering column, under the dash, for voltage, with either brake or turn signal. If no voltage on the proper wire coming steering column, have to voltage to the multifunction switch. If that checks out, suspect multifunction switch or wiring in steering column.