This vehicle was purchased by a friend with the factory tow package. No modifications were made before my purchase three years ago. I installed a factory brake controller for a travel trailer I purchased. The software was enabled with Forscan, and the dealer updated the software to the latest available. Even with a new seven way plug, the truck displays ‘trailer disconnected’ when using the slide brake and also never shows any output when braking. The brakes do engage but very mildly. The travel trailer brakes normally on my other vehicle. There are no fault codes and no obvious connection issues. The dealership today said they do no know the cause and would likely be unable to resolve it.