First experience with diesel & hills

[planopat]

Left the security of hot flat Texas for hot hilly Pennsylvania in my 2017 38A. Following the accepted advice of going down the hill in the same low gear that I climbed the hill has not been too much of a problem but there were a couple of occasions where the transmission would not allow me to downshift while going down the hill, like when I decided I wanted to slow down even more. Other times the selected gear matched the actual gear in the digital display of the push-button shift selector and thereby acted as I had expected. Must one always preselect the gear manually to "lock" the selected gear? I do make use of the engine brake. Also, what's the purpose of "mode" button? Maybe that's the answer to my question. Advice would be appreciated.

[dan-nickie]

Your transmission will protect itself by not downshifting if the RPM is too high. Occasionally you have to use the brakes to slow it down a bit for it to downshift another gear. Just don't ride the brakes all the way down the hill.

I use the engine Brakes in the mountains and seldom have to manually downshift. If the speed gets a little higher than I want, I just press the brake pretty good to slow it down and it will downshift itself.

Use the mode button in Flatlands or small Rolling Hills. It changes the shift RPM and tries to stay in high gear as long as possible which should increase your fuel mileage.

[dan-nickie]

It sounds like you're trying to use the transmission gears and or the engine brake to do all of the work. Those will not slow you down but just help you maintain a certain speed.
Maybe read too much on these forms about being easy on your brakes going down the Hills you might be over cautious on the brakes. Don't worry so much about it use the brakes to slow down if necessary. Just don't ride them for a long time.

[Oscarvan]

I never touch the transmission controls.

Down hill the engine brake is on.... If the speed is too high and the tranny won't down shift by itself make short relatively firm brake applications to slow down to a speed where it will down shift, then let off the brakes to let them cool.

[TheWolfPaq82]

MODE BUTTON: On my 2014 GMC 2500HD diesel, the Engine Braking will not engage unless I'm in "Tow Mode". Don't know if others are like that, but mine is. Down hill, all I do tap brake and it will downshit if needed.

[mlwilliams808]

I also had a little issue with the downshift on my 38C, I was going down the West side of Vail pass (10,666’) and had a hard time keeping it whoa’d up. The brakes were a tad smelly by the time I got to the bottom, I did have a toad with the stay and play system, pulled into the rest area at the bottom to let the color return to the white knuckles. I don’t imagine that I’ll find another downhill that severe.

[Igave]

There will be extremes that the machine may only see a very few times in its life, if ever. They really don’t commonly program for those I don’t think. On those, I feel you just have to ease down and use your common sense. At least on my mh there is no “tow/haul” although my diesel pickups did. The Allison is pretty darn good. The secret is not cresting and starting downhill too fast to begin with. I do like oscarvan does on some pretty steep grades here in the Rockies and that works well. Don’t “ride” them the whole or even much of the way or you’ll overheat the brakes. Just part of the experience and points up how important to be thinking ahead at all times. Have fun with the travels,

[Walholler]

I have a 2015 Chevrolet 2500HD diesel with the exhaust brake. When I am towing our 5th wheel, I have the tow/haul selected. On long downhill grades, I engage the exhaust brake by tapping my foot brake, the transmission will down shift and the exhaust brake comes on. I usually have to disengage the exhaust brake or the truck will slow down to a crawl, then reengage the exhaust brake when truck speeds up. I never use the foot brake for slowing the truck on long grades.

[bareftn]

Originally Posted by Walholler

I have a 2015 Chevrolet 2500HD diesel with the exhaust brake. When I am towing our 5th wheel, I have the tow/haul selected. On long downhill grades, I engage the exhaust brake by tapping my foot brake, the transmission will down shift and the exhaust brake comes on. I usually have to disengage the exhaust brake or the truck will slow down to a crawl, then reengage the exhaust brake when truck speeds up. I never use the foot brake for slowing the truck on long grades.

I am not sure how a exhaust brakes works in a chev but in my western start as soon and I touch the throttle the exhaust brake lets up and wont kick in unless I let up on the throttle. Its always set loaded or empty

[rock-rocker]

I tow a 15k 38' 5th wheel with a 2018 GMC 3500 4x4. I just let the truck do all the work as I hope it is designed. After the initial setup (In Tow/Haul, Exhaust Brake on, Transmission Overdrive off (5th gear the highest it will shift into)) everything just works as a charm for me. In this set up the speed downhill is maintained very well with the exhaust brake and minor braking and going up hill with the transmission only able to go into 5th the the EGT only once in a while gets up to 1200 - 1225 degrees for a very, very short time (spikes). Living in the foothills of California in 100 + degrees works the truck pretty good and proves to me I made the right choice for the setup I have.