The taillight goes on and off. I think I might have a short in the wiring somewhere.
This is a common issue. The bulbs in all the exterior lighting on a vehicle is mounted on a plastic socket. The socket is where the wiring that connects the bulb is housed. Over time these sockets get hard, malformed, and brittle due to the heat of the bulbs themselves. This happens more often and even occurs sooner if you use the high intensity aftermarket light bulbs. When the socket gets damaged, it will no longer make good connection to the bulb causing the condition you are describing. The usual repair is to replace the socket. I would have a certified mechanic verify the cause of your taillight going on and off and advise you on an appropriate repair.