Freightliner turn signal issue

Hey guys!
I have a 2015 freightliner cascadia with close to 550,000 miles and i m having turn signal issue. The switch does 4 things, turn signal wipers washer fluid and high beam. All of it is not working. I have changed the turn signal switch 2-3 times, changes all relays and fuses then went to the shop they diagnosed it and found the SAM CAB needs replaced since water was leaking from the windshield area. Now after we changed it, the problem came back. And i swear to god whenever i feel to take it back to the shop, the turn signal starts working like the whole thing.
What do you guys think? Any advice would be greatly appreciated.