BLW

I use tow haul mode in auto.My torque converter will not kick in under 40 mph.i believe something is not right with this truck

Even in 1st gear truck just keeps gaining speed if im not standing on my brakes,trailer brakes are what saves me from cliff diving

Thanks for the reply my truck doesn't have hill decent option.These hills can be 1/2 mile long and if im not riding the foot brake an manually activating trailer brakes id go over the cliff and even doing this front brakes were smoking like there were on fire,truck does not hold back with exhaust brake at all.So i wonder if it works when it normally [pavement]i can hear/feel the torque converter engage.I do try using the cruise control but i must be going 40mph for it to set then manually lower it be getting to 40mph is not safe on these roads.Just to fast

First time posting i really need some help. I have a 2019 HD3500 Denali dually. I tow a 25ft gooseneck total weight most often 17000lbs travel 120 miles round trip though the mountians can be fairly steep my exhuast brake does NOT work on gravel roads at all get up to 40-45 mph trying to set it then as soon as i hit black top it works.Do these trucks not work on gravel,risking my life.Any help would be really [email protected]