NHTSA Complaint #11425212 — 2019 FORD F-250

when my headlights are on, many times my rear lights do not work. This has never been so when first turned on but they go off later (I have after market side marker lights on my truck so I can see this). If I move the headlight switch one direction or the other, they will come on, Then I can move it back and they will stay on. May not happen again for days, or may happen again in minutes. I spoke with the dealer, and they have no bulletins about this issue and can not address until they stop working all together. Since then I have been watching trucks of this body style and see them go past with headlights on, then I look in my mirror and many do not have any tail lights lit. In this week alone I have counted 17 trucks with no tail lights when head lights are on. In a standard pickup that does not have side marker lights it would be impossible to know this is occurring. I bough this truck new in June of 2019 and had noticed that pulling my trailer, that many times the trailer side marker lights would go out driving down the road. I assumed the trailer had an issue. It wasn't until April 16, 2021 that I noticed this issue. I had an after market body installed after removing the pickup bed, and the following day, I noticed this issue. I assumed a ground issue with the body install, but later that day they came on and stayed on so I assumed the ground during installation had been faulty and resolved itself. This week I came out of a store with truck running because my help was inside truck and noticed the tail lights were not on, but head lights were. Once I moved switch on notch, they came on as described above, that is when I contacted Ford Dealer to no resolve and began watching other trucks and discovered I am not alone in this issue.