I went out to the trailer at the storage unit last week and the running lights were on and nothing was connected. So I asked the question on the Oliver Forum and got excellent help. The plug that connects to the truck when you ought to have lights (and brakes!) had a short and I had to take the end off the plug, clean the connections and then sprayed it with electric connection cleaner. I could have replaced it but It cleaned up well so I don’t think that is needed now. Just another maintenance type of job I did not even know you needed to do. Always learning something. Anyway, no ghost lights. Yay.