I have a 2018 GMC HD Denali with a Duramax. Great truck, except that I continue to have break controller issues. Now I’m out of warranty and it just went for the 4th time. The dealer back home in Canada has been replacing a module aboveboard spare tire. It also went on me while ion Florida and the dealership repaired although I’m not sure how.
Just went today. Not while towing but within 30 minutes of having as carwash. The 30amp fuse under the dash is fine. How can I tell if its the module Or if it is the relay I hear so much about?