1998 Oldsmobile 88 Turn Signal and Horn

Welcome to the forum, if the two problems are connected, it may be the wiring circuit in the steering column. We can check the systems one at a time. As far as your turn signals, the turn and brake lites at the rear use the same bulb filament, just not at the same time, the lower brake lites are wired through the turn signal switch. I'd have to check the turn feed to and from turn signal switch. You can check the turn fuse--20 amp, fuse block, left side of dash, that circuit goes hot when you turn on the key, use a testlite.