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.

 

[RickB]

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

++1 .

 

[Superduper]

The truck is a 2012 with the Allison. Performance is fine in normal mode and in T/H mode, seems like the rpm's run high and won't up shift quick enough as it holds the gears longer. Mileage definitely takes a hit. I figure higher line pressure is desirable for greater clutch holding power but the more aggressive gearing action really isn't necessary as this truck has more than enough power with the normal shift program. The 2012 also has exhaust brake feature too. Last time I towed 3000 pounds 400 miles, the truck didn't even notice the load back there and seemed regular mode was best/fine with no abnormality with tranny temp (145 +/-).

 

[JPRambo]

I have an 2003 Silverado 4.8 lt with T/H mode. The manual says to use T/H mode with 500 lbs or more in the bed,or towing a trailer starting at the same weight.
I haul 800 to 1000 lbs in the bed and with the assist of a weight distributing hitch haul a 21 foot camper. The camper usually is loaded to about 4000 lbs.
I have hauled it 650 miles 8 or 10 times in the past couple years. I only use T/H mode to start off and get to highway speed. At speed I usually turn it off. The last 100 miles or so there are a lot hills so back into T/H mode. The truck has 126,000 miles and still going strong.

 

[jeffsw6]

There is actually some guidance in the owner's manual on this topic. Whether or not you use the T/H mode is entirely up to you. Your transmission has an oil temperature gauge and even if it isn't presented on the dash, the computerized stuff will cause it to shift to a lower gear to pump ATF more rapidly through the cooler if required. If it starts to overheat it is supposed to go into a limp mode before it can do permanent damage. This would be indicated on the DIC.

We talk a lot about transmissions on this forum, but don't forget about your differential service. If I was preparing for your kind of trip I would have my diff lube done if it is approaching a service interval.

 

[Superduper]

We talk a lot about transmissions on this forum, but don't forget about your differential service. If I was preparing for your kind of trip I would have my diff lube done if it is approaching a service interval.

The truck only has 4k miles and I changed the oil with 15/40 Delvac just prior to the trip as I didn't want to trigger an oil change alert during the trip. At the lube service, the diff was checked and topped off (I guess factory fills them a little low).

 

[Bigkrank]

A 2012 with an Allison is a beast, no comparison to earlier models. I have a 2007.5 LMM and as GM says, no need for tow/haul unless more than 8000#.

With the 2008 5.3 gas we use tow/haul when anything is hooked to it.

 

[jeffsw6]

On the Allison it really is not a "self preservation system," though. It has temperature feedback into the shift algorithm that works no matter what mode it is in.

 

[Superduper]

........, and as GM says, no need for tow/haul unless more than 8000#.j

I read my owners manual and didn't see this spec/ recommendation/ guidance. Only a description of what it's for.

 

[crashz]

Both of my GM trucks (2004 1/2 ton and 2012 2500 gas) act rough when using tow/haul while unloaded. However, once loaded with even a moderate weight, they smooth right out. With the new truck, an empty trailer is too light (say 2000 lbs), but with my tractor on (~5000 lbs total) tow/haul performs similar to normal driving. The higher RPMS are noticed, but the harsh shifting is smoothed out entirely.

If it were me, I would run the truck in Tow/Haul mode. Thats what its there for and by doing so, you won't be guessing.

 

[Jd5203]

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 the tow/haul mode does is keeps you in the gear longer running the rpms higher and giving you more torque allowing less strain on your transmission and truck and also allowing you to get up to speed more quickly than if it were changing regularly because it keeps your rpms from dropping to lowly while shifting. Also you only need to youse while pulling trailers and for high performance. Also it makes your trans to shift down quicker while slowing down allowing you to hold back your load better.