Trailer lights are impossible. I used to have a Toyota, and they had some alien wiring scheme that made it impossible to do a trailer right.

Then I had one that never worked. Turned out that the ground wire was connected to a piece of metal that was painted. That's a no no. Has to be bare metal.

Sometimes, they just stop working. They are liable to do anything. Go out at bad times. Work when you think they are broken. Blink off and on. Heck, sometimes the yellow lights will burn red, and vice versa. They make no sense to me whatsoever.

They are very similar to women.