Need turn signal wiiring diagram for 2011 freightliner columbia

What are the symptoms? Do they work with the trailer disconnected? When you put on the right hand directional do both the right and left dash lights light up?

 

If have a 2 tail light system and your brake lights work, I'd say that your issue is in the front or side signals. Gives you 1 less wire to trace. If you have 4 tail lights, that wont help.

 

I would be surprised if the problem were inside. Wires usually chafe and rot away outside. Have you traced all the wires outside back in? I've seen wiring diagrams for trucks and you will not like what you see

 

Sorry, I don't have access to any Columbia's to get wiring. It wont help you now, but for future reference, go to www.accessfreightliner.com and register. They give out free access to parts, wiring diagrams and some service info to owner ops. They may make you verify ownership and it'll take a week or two to get.