1998 Toyota Camry my horn and dashboard lights

Hi Jesse, the problem with the horn is usually the wiring circuit in the steering column. You can also check the horn relay in the fuse box under the hood and the horn fuse. You can unplug the relay, use a testlite, see how many terminals are hot? You can take the connector loose from the actual horn, if one wire, that is voltage. You can use jumper wire from battery voltage to horn, just to see if horn will work. Use inline fuse on the jumper.