Tow/ Haul mode VS normal D

tripleb · February 4, 2017

Looking for opinions on what is best for the transmission. I recently purchased a camping trailer … it’s only 18’ with dry weight of 4100lbs. I am guessing that it’s “ready to camp weight” at about 5500lbs. I had to take the trailer back to the dealer for some warranty work. When I towed it back (approx. 40 miles of mixed city/highway) I reset my mpg display and put the transmission in “Tow/Haul” mode. Checked the mileage when I arrived at the dealer and the display was showing 8.8 mpg avg.

A few days later, I returned to pick up the trailer. I reset the mpg display and put the transmission in “D”. Checked the mileage when I arrived at the house and the display was showing 10.8 mpg avg.

Should you always use “Tow/Haul” mode when pulling a load or should you use it when road conditions dictate … hilly conditions and such.

MikeNH · February 4, 2017

There is never an absolute. You need to pay attention to what the transmission is doing, see if you feel it is shifting too much or if temperatures are getting higher than you'd like. I don't have tons of experience towing and only did so in the Silverado once but I pulled a UHaul trailer to Michigan that was probably somewhere around your dry weight and did not use tow/haul mode as I decided the truck was fine without it. I ran it in M5 until things flattened out west of New York but other than that it was fine and didn't get above 200 until I was stuck in traffic in Cleveland which T/H wouldn't help anyhow.

Chevor · February 4, 2017

I mainly use tow haul below 50 mph to keep torque converter locked in lower gears.

I love it in stop and go traffic, T/H on holds a gear longer. Can almost use only the accelerator pedal, on to speed up and off to slow down.

dcheeseman · February 4, 2017

I personal use the manual shifting the gears myself when towing a trailer. I like having the control over it myself.

For flat roads and interstate driving I'd use "D"

For hilly roads and city driving I'd use Tow/Haul mode.

The whole purpose of the Tow/Haul mode as you probably know is to raise the shift points to get the truck in a better power range. Also downshift sooner to help slow down the truck.

Either way you should be fine as your truck was designed to operate in either mode.

Daniel

Edited February 4, 2017 by Cheesedaddy

sdeeter19555 · February 4, 2017

I mainly use tow haul below 50 mph to keep torque converter locked in lower gears.

I love it in stop and go traffic, T/H on holds a gear longer. Can almost use only the accelerator pedal, on to speed up and off to slow down.

This is what I do as well...

And as soon as I hit 60mph on the interstate, it's off so the trans will shift into 6th, otherwise you have to run 70mph to get into 6th in T/H. And it stays off unless I'm in hilly terrain or below 60mph.

Plus the added engine braking is nice...

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2017HD · February 4, 2017

The manual for my 07 2500 recommends tow/haul mode if you are towing/hauling greater than 50% of the rated capacity of either payload or tow rating.

I am towing just over the 1/2 mark and because most of my towing involves hills I use T/H all the time. It does two things for me - keeps the engine above 2000 RPM and downshifts on the down hills.

SouthpawHD · February 5, 2017

I like using the manual shift as most trailer tires are not rated for speeds above 65mph, and at that speed the RPMs are kind of low in 6th gear.

Big Whiskey · February 5, 2017

I've yet to tow anything with my new 2500HD, but I have lots of practice towing with half ton trucks. On multiple trips from Illinois to Colorado with our camper, I never used D because my trucks couldn't hold 6th gear (or 4th gear on my older trucks) while loaded. On the old 4-spd, I would drop it in 3rd. And, on my last two 6-spd trucks, I would always use M5. I liked tow/haul mode in the city, and when towing in changing terrain (hills of Missouri and mountains of Colorado). Acceleration and engine braking were greatly improved. But, I also noticed a drop in mpg when using tow/haul because it holds lower gears longer. When towing across Kansas, I would just use M5 (no T/H) and let it do its thing. The only time I ever had any issues with transmission temps was trying to maintain speeds on mountain passes.

Cowpie · February 5, 2017

I have a preference for the manual mode. Especially on the rural, hilly highways I frequent with loads and trailers. Upshift when I want, downshift when I want. Stops a fair amount of gear searching that goes on or holding a gear too long when shifting up would be appropriate. And decide the top gear limit. Can keep the RPM's low when full power is not needed, and keep it in a more appropriate gear on the harder pulls. Tried the tow haul mode once. Not motivated to use it again.

Edited February 5, 2017 by Cowpie

Skeld · February 6, 2017

One thing I don't like about Tow/Haul...if you are using the brakes on a downhill it sometimes decides to downshift enough to cause a near redline incident. Anyone else have that issue?

For my light towing, 4500 pounds maybe, I don't think Tow/Haul is necessary. This 2500 transmission is a lot more aggressive than my 1500s were. It behaves a lot like a 1500 does in Tow/Haul when in regular mode.

Edited February 6, 2017 by Skeld

SouthpawHD · February 6, 2017

One thing I don't like about Tow/Haul...if you are using the brakes on a downhill it sometimes decides to downshift enough to cause a near redline incident. Anyone else have that issue?

For my light towing, 4500 pounds maybe, I don't think Tow/Haul is necessary. This 2500 transmission is a lot more aggressive than my 1500s were. It behaves a lot like a 1500 does in Tow/Haul when in regular mode.

I haven't had mine downshift quite like that, but aggressive downshifting allows you to use the motor to slow down and save the brakes of the truck and the trailer. It's a good thing.

sdeeter19555 · February 6, 2017

One thing I don't like about Tow/Haul...if you are using the brakes on a downhill it sometimes decides to downshift enough to cause a near redline incident. Anyone else have that issue?

For my light towing, 4500 pounds maybe, I don't think Tow/Haul is necessary. This 2500 transmission is a lot more aggressive than my 1500s were. It behaves a lot like a 1500 does in Tow/Haul when in regular mode.

That will lessen with time and use...as it learns your driving habits.

Mine would redline with just touching the brakes when I first got the truck, now it takes some braking and a little coercing (a little snub braking) to get it to drop gears...

I only use T/H when towing a loaded trailer...when skating empty (empty is 2400#), I don't use it. When loaded, I'm in the 6k to 8k range, and again only use it when off interstate. I will use it when hauling, just for the grade braking.

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Edited February 6, 2017 by sdeeter19555

Skeld · February 6, 2017

I haven't had mine downshift quite like that, but aggressive downshifting allows you to use the motor to slow down and save the brakes of the truck and the trailer. It's a good thing.

Yeah, I'm aware. I'd just prefer that it not decide to downshift to 2nd gear when I'm going 55 MPH.

ChevyTech77 · February 6, 2017

T/H mode is only supposed to be used if you meet or exceed 70-75% of the vehicles rated capacity.

I use it pulling my 8,000 lb camper because well, it needs it. Grade braking and engine braking are great features that really help to keep things under control while using t/h.

Now my 4,500 lb snowmobile trailer? It's a waste of time. M5 is all I use to haul that. If it's u loaded, I just leave the transmission in D.

Cowpie · February 7, 2017

Yeah, I'm aware. I'd just prefer that it not decide to downshift to 2nd gear when I'm going 55 MPH.

LOL. Yeah, I much prefer deciding when a downshift is warranted, and not at such a time as to put the RPM's on the roof. If it takes putting RPM's that high to get a modicum of the grade braking job done, then some sort of auxiliary drive line braking would be a better option or improved transmission fluid channeling to provide better down grade speed management. And have it such that the operator could make the decision on when it should be engaged. Oh wait.... that would cost money and make sense so GM would never opt for that kind of a solution.