Weird electrical behavior

I have a 93 Taurus. Recently it has begun to do weird electrical things. Turn signals stop flashing when I touch the brake, won’t flash at all when headlights are on. The dashboard signals flash in opposite phase with the radio dial. Sometimes the alarm dinger dings for no purpose. What questions do I ask at the garage? Is this a dealer thing?

Could be a dirty ground wire from the engine block to the frame or fender. The end that is not on the engine is usually the bad one. This is a long shot of course, but it used to work wonders. Some car have a badly grounded dash, usually caused by a loose wire. The battery cables may need a cleanup.