I tow a 9500 Lb 5th wheel with my 2013 Silverado 2500 HD. It is stock with no mods. How and when is the tow haul button used? Does it supply engine breaking when going down hill? Will it downshift? THis is the first chevy I've owned in Years. Always Ford Before. I know how it works in Fords but not in my Silverado. I pick up my new to me trailer today.

Tia

Mel