Pete 579 no left turn signal on trailer

I am having the same exact issue on my 2023 Pete 579. How did you solve the problem?

 

My 2023 Pete 579 is having the same exact issue. How did you resolve the issue?

 

Do you happen to remember which relay ID you changed? What's the name for that relay?

 

I have a 2014 579 that had the same issue I checked every fuse,relay,wiring harness and connection I could find with no sucess. Finally gave up and took it to dealer, they found the Chassis Node had a crack in it and water had got inside. The Chassis Node is located under the cab on the outside of the truck about where your left foot is when you are in the drivers seat its a square 4x6 black box about 1 inch thick with 2 or 3 plugs going into it. It's not easy to get at and you will need to remove the front left fender extension to access it. They are not cheap new and will need to be programed by a Peterbilt Dealer to work with your particular truck. Since having this fixed over a year ago I have not had any more lighting issues. Hope thus helps.

 

FYI, My 2022 Pete 579 had this issue. It was the N2 fuse under the hood. It does not say anything about (Trailer) on my diagram, but it was the broken fuse. It says “SCM F5”.