Tow/Haul mode -- must use?

[Superduper]

Here's the situation...

2500HD Silverado w/ Duramax.

Will be going approx 1500 miles.

Estimating will have approx 2000 lbs in the bed.
Estimating will be towing 4500 trailer.

Do I need to have truck in tow/haul mode all the time or only when I need more aggressive performance? Truck performance feels fine in "normal" mode but I don't want to damage tranny.

 

[JJZ 109]

If the truck isn't laboring, I wouldn't worry about it too much. Maybe on hills I would use it if the truck started to lug, but to keep it in tow/haul mode for the whole trip probably isn't so great for the fuel mileage.

 

[Bladehauler]

I have a 04 dodge 3500, when towing a heavy load ,I start off in tow mode and about 5o mph i kick it out and let it shift to od. My dodges trans is not as stout as your allison, so I think youll be fine. Do you have a trans temp guage on it ?

 

[Deere Dude]

Here's the situation...

2500HD Silverado w/ Duramax.

Will be going approx 1500 miles.

Estimating will have approx 2000 lbs in the bed.
Estimating will be towing 4500 trailer.

Do I need to have truck in tow/haul mode all the time or only when I need more aggressive performance? Truck performance feels fine in "normal" mode but I don't want to damage tranny.

What does the owners manual say? My 02 Duramax has a lot more power getting up to speed in Tow/Haul mode. It brakes a lot nicer when slowing down and also when riding the brakes just a little going down a fairly steep hill, it seems to kick in engine braking. When finally up to speed, 60-75 MPH the RPM's slow down or goes into overdrive, and are the same as when not in T/H mode anyway. Pulling a super heavy load when up to cruising speed, you can take it out of T/H mode and the RPM's stay the same as if you never had it in. The mileage won't suffer once in cruising speed and when not up to cruising speed the extra RPM's help getting there. It is just more aggressive getting up to that point.

If I had just 2000# in the bed, I probably wouldn't mess with it just because I'm lazy, but pulling a trailer with it I surely would. But when the engine is cold, I baby it because the engine really seems to scream. But after a few minutes of babying it, that seems to go away and then running in T/H mode is nice. People seem to be afraid to use it for some reason, and I always had the same thought process until I tried it. It is just something to get used to. It doesn't hurt anything, in fact I would wager it helps on brakes and transmission wear.
I pull a 17,000# camper and a 10-11000# trailer and also a 2500# load trailer and it always seems to run better in T/H mode.

 

[Bigkrank]

Unless it's hilly I never use tow/haul mode unless towing over 8000#, my owners manual says something similar.

 

[Diamondpilot]

I am going to go against the grain and say use it. The Ally does not prevent 5/6th gear (OD), depending on the year with Tow Haul Mode. I was lucky enough to replace two transmissions in a 2003 2500 Dodge and will tell you they are very very expensive. The small savings you would have gotten can be washed away by just a fluid change if all you did was burn it. Use Tow Haul Mode. It's there for a reason.

I tow about 10,000 miles a year for the last 20 or so years and other than the one truck have never had a tranny issue. These are not small loads either. Average weight over these years has been right around 12,000#. I always use T/H mode unless I am taking a empty boat trailer or car haul trailer to get something. Once it loaded it goes right back on.

As for switching out of T/H Mode once up to speed that does not work either. Back in about 2004 we were in a boating caravan taking 6 or so 8,000# to 16,000# boats from Cincy to Lake Of The Ozarks in Missouri and the guy towing the smallest boat with a 1 or 2 year old 360 V8 4X4 Ram took his out of T/H mode. Within 10 miles it was smoking from under the hood. We pulled over and it had boiled the tranny fluid and it was coming out the dip stick and pouring on the exhaust. Long story short it had to be towed to the next town and a full tranny service was preformed. It has been fine since and he still drives the same truck, seen him last weekend at the lake, but he dodged, no pun intended, a bullet.


Chris

 

[LD1]

I dont think you mentioned what year the truck is???

On old trucks, tow/haul was really an OD off button. Thats about all it did. It kept them out of OD so it wasnt constantly hunting for gears.

BIG difference on newer stuff with electronic trannys. Tow/haul mode usually firms up the shifts so they dont wear on the clutches as much, shift at a little higher RPM, sometimes run a higher line pressure, etc. And I am dont sure you your specific truck, but my 05 dodge STILL will go into OD even when in tow haul mode.

I see no reason to NOT put it in t/h mode when you are actually towing and hauling:thumbsup:

 

[ericher69]

+1 use it unless a light load 1500 or less lbs is my rule

 

[sld]

Just because you keep it from shifting into the top gear does not necessarily mean you kill your gas mileage.

When under a heavy load, running an easy 2600 to 2800 versus a labored 1800 to 2000 rpms, your mpg will not take a bad hit...if at all.

 

[hosspuller]

First, what other truck brands do & say aren't applicable to your truck. I believe you have an Allison auto transmission in your truck. The t/h mode is not just aggressive performance. It locks the torque converter to reduce heat build up. To see this effect, when towing, in normal mode, as the trans down shifts up a hill, switch to t/h. The engine rpms will drop further as the TC locks.

As for your question, I would engage t/h in hilly areas and in stop /go traffic. Otherwise I would drive your load in normal mode.