I feel your pain!~I just spent a LOT of time chasing electrical gremlins on my "new" car. It obviously spent a lot of time outside as a neglected car. My headlights, taillights, instrument lights, horn, etc were all non functioning, or sporadically functioning. We started at the fuse panel, took everything apart, removed the color coded paper and lightly sandblasted (very carefully!) the connectors, cleaned and blew it dry. It seems mice had been living in the fenders in the hollow area under the fuse panel and had chewed several inches of insulation off of several wires. There were loose or disconnected wires at the instruments themselves, and we rebuilt the tail light units. Still intermittent tail lights. It seems the light switch itself at the dash had a wire for the tail light, that was broken down to a single filament, which finally broke. All is working now, days later! It was a slow process of checking, cleaning, replacing wires and making new connections everywhere but ultimately, with good results. The process cannot be sidestepped as at least for me, it's always the 5th and last thing I try that ended up being the winner. Good luck