Some thoughts on trailer tow mode

[R&J Silverback]

I have found that the tow mode is used when one is pulling in the hills . If the tranny wants to down shift and the up shift to quickly the put it in tow.as tow will run a higher rpm and lower mpg.if your tv isn't working hard (lower rpm) the better off you are

[Mr. Dan]

Originally Posted by mcmartinez

My understanding is that in TOW it doe snot shift into overdrive. I use it sometimes, particularly on hills, but I don't see much difference. 2010 Ford F-150 Super Crew Short Bed Crew Cab 5.4L V-8 6-spd auto 2x2 - 9,800 Lbs. towing capacity. Pulling a 2703WS Rockwood Super Lite (6,400 Lbs. dry weight)

See above post(s) where it is stated that TH does not lock out overdrive - at least in some Fords.

It is obvious TH does not work the same from manufacturer to manufacturer nor even year to year in a particular line. With TH on, my truck will tow in 6th year (5th and 6th are both overdrive same as was posted above) AND in 4-cylinder mode many times.

[Witch Doctor]

Originally Posted by Semperfi24

Cant speak for other manufacturers, but Ford recommends Tow/Haul mode for accelerating from a stop, bumper to bumper traffic, terrain with lots of ups and downs, etc. And if you are on mostly flat highway (already at speed) they recommend you turn it off as a way to gain fuel mileage. As I understand it with my truck (6 speed auto, eco boost) the Tow/Haul will keep you in 5th gear, and if you shut if off the truck will then use 6th (which is why you get slightly better fuel mileage). That was what I was told by a Ford Tech.

I agree my F250 will do the same, it will lock you out of overdrive, which burns more fuel. It will also hold you longer in the gears as it moves up from first. In Tow haul I will show much higher RPM before shifting. I use it in the hills climbing and going down. Or stop and go traffic. I get to speed and shut it off on the flat highway so I can drop my rpms. On Ford Tow haul, locks you out of overdrive. I never seen any trans temp difference either on or off. But I also have a good truck F250 with the 6.0 and 133,000 miles on it. The more miles I put on it the better it runs..... Knock on wood

[Toby]

Originally Posted by gljurczyk

I agree my F250 will do the same, it will lock you out of overdrive, which burns more fuel. It will also hold you longer in the gears as it moves up from first. In Tow haul I will show much higher RPM before shifting. I use it in the hills climbing and going down. Or stop and go traffic. I get to speed and shut it off on the flat highway so I can drop my rpms. On Ford Tow haul, locks you out of overdrive. I never seen any trans temp difference either on or off. But I also have a good truck F250 with the 6.0 and 133,000 miles on it. The more miles I put on it the better it runs..... Knock on wood

FWIW you can also lock out as many gears you want by using the downshift button in automatic mode on the Ford (for those with manual shift option). I'm not sure why I would ever do that on purpose but it works.

[B and B]

Originally Posted by mcmartinez

My understanding is that in TOW it doe snot shift into overdrive. I use it sometimes, particularly on hills, but I don't see much difference. 2010 Ford F-150 Super Crew Short Bed Crew Cab 5.4L V-8 6-spd auto 2x2 - 9,800 Lbs. towing capacity. Pulling a 2703WS Rockwood Super Lite (6,400 Lbs. dry weight)

Thats my first combo, except 2009 truck. I found the V8 did not have the torque of the Eco for sure. The transmission ran hot and was rarely in 6th. Eco does make 6th on most flat terrain with gentle grades.

[dustman_stx]

Originally Posted by gljurczyk

I agree my F250 will do the same, it will lock you out of overdrive, which burns more fuel. It will also hold you longer in the gears as it moves up from first. In Tow haul I will show much higher RPM before shifting. I use it in the hills climbing and going down. Or stop and go traffic. I get to speed and shut it off on the flat highway so I can drop my rpms. On Ford Tow haul, locks you out of overdrive. I never seen any trans temp difference either on or off. But I also have a good truck F250 with the 6.0 and 133,000 miles on it. The more miles I put on it the better it runs..... Knock on wood

You have an older 6.0 PSD. Older Fords did lockout OD. Not the case with Ecoboost trucks. If anyone wants to test it, just turn it on and head down the road unloaded. It will go into 6th. And will with a load until the load offers enough resistance the tranny determines it needs to hold 5th. Keep loading and you'll finally hold 4th.....

[B and B]

Originally Posted by Toby

FWIW you can also lock out as many gears you want by using the downshift button in automatic mode on the Ford (for those with manual shift option). I'm not sure why I would ever do that on purpose but it works.

I use the lockout all the time on ice and snow to get maximum dynamic braking with the engine.

[dicky1243]

Use the TH It's cheaper than new tranny If I don't use mine the trans. temp goes up about 50 deg.s I have a 3500HD GMC Allison tran. pull Sierra 365saq loaded 15,500 pulls the hills good but would not if not in TH I like having a dually for more stability on windy days and it doesn't feel trucks going by.
I have 330,000 Miles on truck, Do to a bad lower radiator clamp I had to replace the
engine 30,000 miles ago. The new eng. runs good gets 23 without trl. and between 11 and 17 with the trl. depending how fast I drive, given the choice i'd get another GMC can't feel it shift lots of power. We are full timers

[OldCoot]

Originally Posted by TURBS

Not true at all.
At least on gm the trans stays in a lower gear "higher" rpm when tow haul is engaged.

Agree, at least on my weak kneed 05Silverado it doesn't change any shift points, just stays in whatever gear longer until it shifts into 4th. It drops my rpm @ 65mph to approx. 1700 rpm with a 3.23 rear end.

[Blackhat6mike]

Question. Has anyone "burned up" or know of anyone that has "burned up" an Allison tranny?

[MillerTime]

Originally Posted by OldCoot

Agree, at least on my weak kneed 05Silverado it doesn't change any shift points, just stays in whatever gear longer until it shifts into 4th. It drops my rpm @ 65mph to approx. 1700 rpm with a 3.23 rear end.

Sorry, but isn't that the definition of changed shift points??

My duramax/Allison 5speed doesn't raise the rpms in t/h mode. Will not drop a gear once put in t/h mode and holds gears longer and will downshift while braking.
I use it anytime im towing anything except an empty car hauler, and sometimes even when im not towing when in stop and go traffic or negotiating hill and curves at slower speeds- like driving around the Ozarks and around Branson.
Everybody does what works best for thier combo or situation im sure!! The above is what works best for me!!

[dcheatwood]

Originally Posted by dustman_stx

Both mine and my mothers EB (one 2011 and one 2013) use all gears regardless of tow/haul mode. I think your Tech might wanna study a little more. Tow/Haul, at least on the Ford's, is NOT an overdrive off button. They would technically have to lock out 5th and 6th to be an overdrive off button, though.

Same as tundra 5,7L. Uses all 6 gears in tow/haul but shifts at higher rpms.

[dicky1243]

Originally Posted by MillerTime

Sorry, but isn't that the definition of changed shift points??

My duramax/Allison 5speed doesn't raise the rpms in t/h mode. Will not drop a gear once put in t/h mode and holds gears longer and will downshift while braking.
I use it anytime im towing anything except an empty car hauler, and sometimes even when im not towing when in stop and go traffic or negotiating hill and curves at slower speeds- like driving around the Ozarks and around Branson.
Everybody does what works best for thier combo or situation im sure!! The above is what works best for me!!

I have a 6speed Allison and in TH it will progress through the gears as long as i'm stepping on it, it downs when not as soon as the rpm's allow. the original q. was to TH or not I say yes as long as you're
towing a load thats what its for I have a trans. guage and if I don't have it in TH on a 75* day the temp will raise 50* or more. TH trans. have a larger sump to help keep Trans. cool that why TH is necessary.

[dicky1243]

I have a 06 gmc dually with rear drive only 3.83 rearend that is a reason for my better fuel milage when in TH or not

[youroo]

Dicky1243, are you sure about that (383) rear gear? Youroo!!

[dicky1243]

Yes, i have a print out of everything on my truck even the 2" body lift air bags factory inst. All you have to do if you're not sure what is in your truck take the vin. to the parts dept. and ask them to download the original paper on it when made.

[TURBS]

Never seen a gm 383 gear

410
373
342
323
308
In 2006

[MillerTime]

Obviously its 3.73 gears. That's all thats been offered for light duty duramax trucks since they came out with the '01 model
(glove box option code GT4)
And 6 speed allisons have a 2nd od gear that the 5 speed doesn't, otherwise the ratios for the tranny gears are the same. At least per allison, ive never actually counted teeth personally, but ill ask my buddy over in heavy line if i need to know for sure.

[kerrlakelover]

SPECIFICALLY ABOUT THE ALLISON IN 2011 GM/CHEVY 2500HD...
So with all this said and with other forums I've read, I see no absolute about having to use T/H mode. (There is something in the owners manual about 75% of load rating...) On my 2011 2500HD pulling my 14K 5th wheel, I use T/H depending on the situation.
When pulling the 5vr, coming up to speed , or when I anticipate slowing down, I kick it in T/H mode.
Once up to speed, unless I'm in hilly terrain, I take it out of T/H mode. On my last trip I really paid attention to this and found out that if I were running 65mph in T/H mode, my tranny temps actually climbed a bit. When I'd kick out of T/H mode, the temp would come down. So, I'm guessing, you use T/H mode the way it best seems to work for you application. Anyone disagree?
Also, someone said something about T/H increased the tranny fluid pressure which helped the clutches...anyone know if there's anything to this?

[MillerTime]

Originally Posted by kerrlakelover

SPECIFICALLY ABOUT THE ALLISON IN 2011 GM/CHEVY 2500HD...
So with all this said and with other forums I've read, I see no absolute about having to use T/H mode. (There is something in the owners manual about 75% of load rating...) On my 2011 2500HD pulling my 14K 5th wheel, I use T/H depending on the situation.
When pulling the 5vr, coming up to speed , or when I anticipate slowing down, I kick it in T/H mode.
Once up to speed, unless I'm in hilly terrain, I take it out of T/H mode. On my last trip I really paid attention to this and found out that if I were running 65mph in T/H mode, my tranny temps actually climbed a bit. When I'd kick out of T/H mode, the temp would come down. So, I'm guessing, you use T/H mode the way it best seems to work for you application. Anyone disagree?
Also, someone said something about T/H increased the tranny fluid pressure which helped the clutches...anyone know if there's anything to this?

Doubt anyone on here could answer that and have a real working knowledge about it.
I only know one guy who could possibly answer all that, and he works at another dealership now. He can change or program just about anything on a gm vehicle.
I hate to bother him about a forum question, especially since theres gonna be a few that will say that he or "we" don't know what were talking about. But you'd be hard pressed to find a smarter tech than him.