Climbing in the Rockies

I pick the gear I want and use the tow haul and exhaust brake as needed.

Have never used the manual option on our F350, and most of the towing driving we do is up and down grades. Just tow/haul mode and let it do its thing. We drive primarily in CO and WY.

with the newer trucks with tow/haul mode, the truck can probably control the drivetrain better than you can.

Now if it starts hunting for gears or you aren't getting any exhaust braking effect, that's when you might want to take a manual hand in the operations. (Read the manual before hand so you don't make things worse)

Have a 2015 GMC 3500 Duramax. Have made 4 trips through the Bighorns, Yellowstone, Glacier, RMP. All pulling a 12,000# TT. Never once took it out of Drive/tow-haul with exhaust brake on. Very seldom had to touch the brake pedal. It works as designed if you let it.

Standard mountainous terrain gear strategy for pickup truck diesels:

Select a gear going up that keeps the engine in the 2500-3000 rpm range for best pulling power and least heating up.

Select one gear lower than the climb, to go down the other side.

Toolguy5 wrote:
Have a question.
I have a 3500 GMC diesel. My question I when in the mountain areas should I leave it in drive and use the exhaust brake, or put it in manual and shift gears when climbing and descending.
Never been in the Rockies.

tow haul mode, exhaust brake on and cruise on and it will hold the speed your set to. IMHO no reason to use manual mode. Go over the rockies quite often, seldom need to use the brakes with it.

other than a few trips on the interstate we usually are on secondary roads, and many have steeper grades and sharper turns than the interstate by a long shot. should not have any issues on virtually all roads.

BTW get a copy of the "Mountain West Directory" it give good info on most all mountain highways and passes with grades, length, turns etc.

I will be mostly on interstates but will need take some Highways to get where we are going.
Montana, Wyoming and Idaho don't have interstates where we need to be.
So don't really know how much climbing and descending there will be on roads like HWY 12, Hwy 85, Hwy 191 to name a few.

I think the GM and Ford exhaust brakes function like the Ram brake does in auto mode, and if that's the case I think you can just drop it in drive, put it in tow haul, turn the exhaust brake on and have at it. Tow haul tends to cut down on the hunting, and the auto mode will hold whatever speed you set through a combination of modulating the brake and downshifting as needed. I've descended some of the bigger grades you'll find in the western mountains without touching my brakes aside from needing to slow additionally for a corner. It's amazing.

I expect your experience will be much the same as mine has so far, which is to say you'll be very impressed with how the truck performs.

Assuming you are speaking of highways just put it Drive and let the engine and transmission do their jobs. Have never found a need for manual shifting on a highway with my F350, and that includes Colorado mountain passes.

I hope you are talking highway and not scenic roads. I have a F-350 Diesel and we made the trip a few months ago. I used my tow haul feature sometimes and other times I did down shift. There were times I did have to nudge the break still to keep the speed from creeping up a bit. Usually, if you are going down hill there are also bound to be turns too. So keeping the speed low is important. Rather slow and safe than too fast and taking the same way down. If you are in low gear and the speed creeps up just "jab" the breaks to bring it down a few miles at a time.