# Plowing With Tow/haul On/off



## millsaps118 (Aug 13, 2006)

My fellow Chevy brothers/sisters (or anyone that has the TOW/HAUL feature)...was curious to know if you ever use the TOW/HAUL button to push snow? In theory it makes since, but I never tried it.


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## NoFearDeere (Nov 7, 2005)

I have a Ford; I plow without the tow/haul mode activated.


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## jryden145 (Sep 29, 2006)

Plow in low range and it doesnt really matter.

J


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## mayhem (Aug 25, 2006)

Depends on how fast you're pushing snow. Tow/haul just raises the shift points at any given throttle angle. If you're pushing snow at light throttle input and high enough speed to upshift the auto then tow/haul would proabbyl help increase the lifespan of your tranny...I'm inclined to think though that the load the extra mass of the snow puts in front of the truck would keep your right foot fairly deep into the throttle and you are proabbyl not upshifting too soon.

Nothing wrong with it, but I'm not sure there is any benefit either.


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## rgrimes945 (Oct 22, 2006)

*Benifit, I think YES*

The Benefit would be in the life of your tranny. It stands to reason if they want you to use it for pulling a load, don't you think it's a good Idea for PUSHING a load ! My Son and I talked about this very subject a week or so ago and we decided to use the tow feature


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## ThisIsMe (Oct 31, 2006)

rgrimes945;334778 said:


> The Benefit would be in the life of your tranny. It stands to reason if they want you to use it for pulling a load, don't you think it's a good Idea for PUSHING a load ! My Son and I talked about this very subject a week or so ago and we decided to use the tow feature


Makes sense to me. If it cuts down on the number of shifts, it must surely be better for the tranny. Or am I wrong?

Chris


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## Young Pup (Aug 13, 2004)

I use it sometimes while plowing. But I defintely use in between properties while driving. I have plow hanging off the front and noramlly a skid of salt in the back. That is where I think it is beneficial.


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## B&B (Nov 4, 2006)

Use the tow/haul when your actually pushin' snow.It will help the tranny. Moving down the road even with the plow and maybe a spreader in the bed it's not really necessary to use it unless your very heavy and traveling in hilly terrain. It's a good idea to use it when you pushin' snow in a parking lot because the T/H not only raises the shift point's up in the rpm range but much more importantly it also raises the line pressure of the trans.More pressure will allow it to keep the clutch's clamped better so they wont be as likely to slip under a hard load. If it will add life to your tranny why wouldn't you use it?


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## PLOWMAN45 (Jul 2, 2003)

I dont use it


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## Snowman19 (Sep 30, 2006)

I never use it. I just watch the trans. temp gauge.:waving:


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## Antnee77 (Oct 25, 2005)

You guys who don't use it might want to reconsider. Tow/Haul is key. I have it on 100% of the time during any given storm.


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## TRUE TURF LAWN (Sep 12, 2005)

in my 06 i have drive and manual so i just put in manual and shift it to whatever gear i want mostly 2nd.


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## Brian Young (Aug 13, 2005)

POPO4995;334716 said:


> I have a Ford; I plow without the tow/haul mode activated.


Our owners manual said to plow *with* the tow/haul activated. (06F250SD) I know you really dont get going that fast but ours seems to have more power when it stays in the lower gear.


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## mayhem (Aug 25, 2006)

rgrimes945;334778 said:


> The Benefit would be in the life of your tranny.


Depends on the situation I guess. I only do my own driveway so I never get out of first gear anyway, so tow/haul would have zero benefit to me. If you're in a situation where you are pushing snow and you get going fast enough to upshift and then lug the motor then tow/haul is clearly the winning choice and will most definitely help increase the longevity of your powertrain.



> It stands to reason if they want you to use it for pulling a load, don't you think it's a good Idea for PUSHING a load !


From my perspective there is a huge difference between pulling a heavy load on a trailer or in the bed and pushing snow, and that difference is in the speed at which you do it. I can pull a trailer up a ling hill at 40-50mph, tow/haul should defintinely be used to help ease up on the pressure the tranny has to take by keeping it in 3rd gear for a longer time, but I certainly don't push snow at 40mph...again though, I'm just a schmoe doing his own driveway in a 3/4 pickup.



> T/H not only raises the shift point's up in the rpm range but much more importantly it also raises the line pressure of the trans.More pressure will allow it to keep the clutch's clamped better so they wont be as likely to slip under a hard load


Convincing argument right there. I was unaware it also increased the pressure in the tranny, thought it just remapped the computer's shift points to hold lower gears longer. Learn somthing new every day.


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## Mark Oomkes (Dec 10, 2000)

Our trucks are always in T\H, I even ride around town in my 350 with it. I like the response much better. 

We also almost exclusively plow in 1st gear, but I would still recommend using T\H if you're not using 1st gear for the above reasons.


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## lieutlamson (Dec 4, 2006)

Everyone know the trans shifts different in tow/haul. But what it also does is raise the line pressures in the transmission. Basically keeping the trans cooler. I keep mine in tow/haul but only plow roads. By dragging out the shift more with the tow/haul the truck doesnt constantly shift as I go down the road.


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## Antnee77 (Oct 25, 2005)

lieutlamson;335054 said:


> Everyone know the trans shifts different in tow/haul. But what it also does is raise the line pressures in the transmission. Basically keeping the trans cooler. I keep mine in tow/haul but only plow roads. By dragging out the shift more with the tow/haul the truck doesnt constantly shift as I go down the road.


Exactly! Many do not realize it, but there are several benefits to using T/H mode when plowing. It is an absolute must for me.


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## Triple L (Nov 1, 2005)

My truck goes from Reverse to First, Every-Time, even when i'm just driving around, then I'll put it up to 3rd. I've just always used first for plowing because my buddy that has been doin this for 26 years said that it will save your tranny all those extra shifts into 2nd when you let off the gas and then into 1st once you slow down, then into reverse (2 unnessary shifts every push). Just wondering if it will do anything by having the Tow Haul on and have it in 1st or will it not make a differance?


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## Dent82 (Dec 6, 2005)

You should always use it. Especially with a disel, v-plow combo. If I have my plow on I have T/H on.


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## B&B (Nov 4, 2006)

Quote by Meyham: Convincing argument right there. I was unaware it also increased the pressure in the tranny, thought it just remapped the computer's shift points to hold lower gears longer. Learn somthing new every day.[/QUOTE]

Meyham, Glad to see you picked up on that, as few do. Like I said originally the T/H raises the shift points but raising the line pressure is the MAIN benefit when plowing snow.If more guy's realized that, I think they'd use it more. If you pay $30,000 or more for a truck with all the newest technology why would'nt you use that technology to prolong the life of that $30,000 truck?


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## 2004F550 (Nov 13, 2003)

always use T/H, helps downshifting too with all of the weight.


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## Yaz (Apr 13, 2005)

I never use it. Why, when you should be plowing under 10MPH. In real heavy snow I use 4L but that's very ofter when you plow with a storm. I suggest listening and knowing you truck well enough to feel the shifting if it's early and lugging with the load you have on it, buy all means use the tow haul if it helps.

As for increasing line pressure , that's *not* that the case in all transmissions.


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## Rowski (Oct 24, 2005)

I'll have to check in my information system at work to verify...

In a 4L80e the t/h mode does not raise the line pressure. Basically it changes the shift points and the engagement of clutches, more crisp and firm. It is also calculated... meaning that it not just a fixed value. The ECM uses algorithm calculations which take into current load, throttle angle, rpm, engine temp, etc. then compares the data to what is needed for the next gear Then it shifts if the parameters are met.

I'll get a description and operation of the t/h mode posted from my information system.

Derek


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## Brian Young (Aug 13, 2005)

Mark Oomkes;335000 said:


> Our trucks are always in T\H, I even ride around town in my 350 with it. I like the response much better.
> 
> We also almost exclusively plow in 1st gear, but I would still recommend using T\H if you're not using 1st gear for the above reasons.


Mark, have you ever considered a Super Chip? I was looking into them and the Ford guys seem to love them. I found a SuperChip "Tuner" that goes into 3 different modes, and they are supposed to get 25-30 more hp, 15-20lbs of torque and get you about 2-4 more miles per gallon.


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## basher (Nov 13, 2004)

Rowski;335636 said:


> I'll have to check in my information system at work to verify...
> 
> In a 4L80e the t/h mode does not raise the line pressure. Basically it changes the shift points and the engagement of clutches, more crisp and firm. It is also calculated... meaning that it not just a fixed value. The ECM uses algorithm calculations which take into current load, throttle angle, rpm, engine temp, etc. then compares the data to what is needed for the next gear Then it shifts if the parameters are met.
> Derek


Right on, it's my understanding on the newer vehicles the tow/haul is like "chipping" the vehicle
it remaps fuel, ignition, and valve timing, as well as trans shift points and torque converter action.
It effects the vehicle performance from dead stop to over-rev (which the ECM should prevent.)
Unless you are concerned more with fuel mileage then performance or longevity you should ALWAYS plow, tow and haul in the tow/haul mode.
I use it every time i start the truck, I like all the performance the vehicle has to offer. If I want gas mileage i'll drive the Insight.


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## Mark Oomkes (Dec 10, 2000)

Yaz;335546 said:


> I never use it. Why, when you should be plowing under 10MPH. In real heavy snow I use 4L but that's very ofter when you plow with a storm. I suggest listening and knowing you truck well enough to feel the shifting if it's early and lugging with the load you have on it, buy all means use the tow haul if it helps.
> 
> As for increasing line pressure , that's *not* that the case in all transmissions.


SHould be? So does this mean you never go over 10 MPH?

Maybe you could point out which tranny's the T\H mode does not increase line pressure.

I listen and know my trucks, all of them. I can tell in under 5 minutes if there is something wrong that the regular operator hasn't noticed. My listening and knowing tells me that T\H is a must because it greatly reduces lugging, helps with shifting and line pressure and helps with braking.


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## millsaps118 (Aug 13, 2006)

Rowski;335636 said:


> I'll have to check in my information system at work to verify...
> 
> In a 4L80e the t/h mode does not raise the line pressure. Basically it changes the shift points and the engagement of clutches, more crisp and firm. Derek


Derek..You must be a mechanic or something. Your right. Talked to my mechanic today and he he said almost the exact same thing.


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## Yaz (Apr 13, 2005)

Mark Oomkes;335648 said:


> SHould be? So does this mean you never go over 10 MPH?
> 
> Maybe you could point out which tranny's the T\H mode does not increase line pressure.
> 
> I listen and know my trucks, all of them. I can tell in under 5 minutes if there is something wrong that the regular operator hasn't noticed. My listening and knowing tells me that T\H is a must because it greatly reduces lugging, helps with shifting and line pressure and helps with braking.


Wow you must be a expert in your own mind from that statement! xysport Sorry to not to totally agree with you.

I does not increase line pressure as to how you and others are thinking. It does increase line pressure a little because your RPMs are higher at the shift points. But when they are engaged, the clutches will not hold any more power before slipping (Fact). Let's not leave a false sense of security in others here.. agreed

Basically holding shifting to higher RPMs at lower throttle positions, This avoids shifting to early. No line pressure change buy anything other than having higher RPMs Fact is that the shift point and pressure are no higher than at full throttle.

That's why I go to 4L when I'm in a heavy snow.

And yes I plow at about 10MPH maybe a little faster, but I only plow residential.


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## Mark Oomkes (Dec 10, 2000)

Yaz;335931 said:


> Wow you must be a expert in your own mind from that statement! xysport Sorry to not to totally agree with you.
> 
> *I does not increase line pressure as to how you and others are thinking. It does increase line pressure a little because your RPMs are higher at the shift points.* But when they are engaged, the clutches will not hold any more power before slipping (Fact). Let's not leave a false sense of security in others here.. agreed
> 
> ...


Not an expert and no apology needed because all I am asking for is further explanation. If you're going to state something like you did then back it up, otherwise it's like saying Boss plows suck and leaving it at that.

I am not following your explanation because near as I can tell, you are contradicting yourself. In your first post you state it does not increase line pressure in all trannies. In your second post you state it does.

Which ones are you referring to?

In your second post, you state it doesn't increase like we think it does, but it does increase just like it's at full throttle.

So does it increase line pressure or doesn't it?

If it doesn't on all transmissions, please inform us of which ones it doesn't, because as far as I know--which isn't far--both TorqShifts and Allisons do increase line pressure and delay shifting in T\H.

PS The only mind I'm a legend in is LLM Ann Arbor's.


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## Rowski (Oct 24, 2005)

Yaz;335931 said:


> Wow you must be a expert in your own mind from that statement! xysport Sorry to not to totally agree with you.
> 
> I does not increase line pressure as to how you and others are thinking. It does increase line pressure a little because your RPMs are higher at the shift points. But when they are engaged, the clutches will not hold any more power before slipping (Fact). Let's not leave a false sense of security in others here.. agreed
> 
> ...


The 4L80E is a fully electronically controlled transmission.

What you are trying to describing is line pressure that altered by Governor pressure, non electronic transmission.

The electronic transmission does not have a Governor. Pump pressure is regulated by a mechanical pressure relief spring in the pump. Line pressure is modulated by the ECM via the pressure control solenoid valve. The ECM raises and lower line pressure (varies current to solenoid) as is need. All the Tow/Haul mode does is give the ECM another input as to where line pressure needs to be..

On another note...

Majority of the heat generated in an automatic transmission by the fluid coupling, ie torque converter. The clutches and bands do produce some heat but very small in comparison to the torque converter.

Also, on a auto trans that is in healthy shape, when you "power brake" (throttle with brake on and no tire movement) does not mean the transmission is slipping as in clutches and bands. The torque converter is trying to multiplying torque and can't. That is when the fluid heats up.



> Derek..You must be a mechanic or something. Your right. Talked to my mechanic today and he he said almost the exact same thing.


Yes and no... I prefer technician.

Derek


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## B&B (Nov 4, 2006)

Just to double verify,today I got in contact with a guy from ATRA.(automatic transmission rebuilders association) The 4L80E's WILL raise the line pressure via the EPC solenoid when in T/H, especially if it detects any slippage. It wont raise it to a set point across the board but will raise it above the standard point when in T/H (generally 50-100 additional psi.depending apon conditions) He basically said that when the T/H is engaged the TCM will more closely monitor sensor input's and make additional corrections to the line pressure. More or less putting the TCM on high alert.


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## Yaz (Apr 13, 2005)

Mark Oomkes;335939 said:


> Not an expert and no apology needed because all I am asking for is further explanation. If you're going to state something like you did then back it up, otherwise it's like saying Boss plows suck and leaving it at that.
> 
> I am not following your explanation because near as I can tell, you are contradicting yourself. In your first post you state it does not increase line pressure in all trannies. In your second post you state it does.
> 
> ...


My original comment on "not on all transmission" I because I was specifically thinking about the Allison 1000 series found in ¾ and 1 ton GM's. I personally have been working with a well known Allison specialist specifically about adding more holding power (increasing line pressure) because I as well as many others have added extra HP and Torque into our trucks. If was as easy as pressing the Tow/Haul button to increase line pressure to keep clutches from slipping, We wouldn't be spending thousands of dollars to build these things to hold the HP and torque we throw at them. The Allison is adaptive learning transmission. When switching to T/H you might feel it shift harder into gears as well as hold the shifts, that hard shifting will get smother each time but the holding shifts points will not.


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## Mark Oomkes (Dec 10, 2000)

Thanks, Yaz, but what about Derek's (the technicians) comments? 

Are there problems out there with chipped Duramaxes and Allisons? I thought they would handle a lot more power than a standard Duramax would put out.


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## lieutlamson (Dec 4, 2006)

Line pressures are raised in the allison 1000 when tow haul is activated. Simply raising the line pressures alone doesnt make the allison able to handle 500hp and 1000ftlbs. My truck has a complete Suncoast trans and I still use tow haul which seems to keep the trans cooler and less shifting. 

I dont think anyone has to use the tow/haul. Ive tried both and the truck seems to run better in tow/haul when Im plowing. By holding the gear the rpms stay up higher so If I have to give it more throttle the trucks doesnt struggle or have to upshift. When Im plowing down the road in tow/haul the truck runs about 2000rpms.


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## Mark Oomkes (Dec 10, 2000)

Thanks, I didn't mean to imply that they could handle more HP and torque because of T\H. I just thought that they were 'overbuilt' somewhat as opposed to Ford and Dodge's tranny's.

I gotta agree on the T\H with my Fords, I use it all the time.


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## Yaz (Apr 13, 2005)

Mark Oomkes;336524 said:


> Thanks, Yaz, but what about Derek's (the technicians) comments?
> 
> Are there problems out there with chipped Duramaxes and Allisons? I thought they would handle a lot more power than a standard Duramax would put out.


I am very easy on my truck and i have yet limped the trany. Limping is a term when the Allison ratios are not normal . Input and output shaft sensors in it are monitored.

Yes it is common to slip in overdrive as well as other gears with adding over 100Hp and 250 FPT at the rear wheels. There is so much info from Dieselplace.com it will take weeks to read it all. Interesting site with lots of smart trany guys.

I'm running 126+ more than stock at the rear wheels. 310 stock engine minus mechanical loss = about 265+126=301HP + 4 inch exhaust gains. I never been on a dyno, so it's just a guess from what others are doing. I'm very cautious not to beet it. If I was 18 again it would have been broken in a day.


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## Rowski (Oct 24, 2005)

I have very little experience with the allison, just what I have read.

The Allison is a very interesting transmission in its software.

Allison has a nice web site http://www.allisontransmission.com/service/index.jsp

Here is some of the frequently asked questions from the Allisonn web site.

Q. Tow/Haul vs. Normal Mode - What's the difference between Tow Haul and Normal Mode?
A. Tow/Haul (T/H) shift mode significantly changes the transmission's shift pattern to reduce shift cycling and to deliver better performance, control, and cooling when towing/hauling heavy loads. For instance:

* Upshift points are raised at light to mid throttle position to use more of the engine's available power for accelerating.
* Downshift points are raised to enhance engine braking to help slow the vehicle.During deceleration, the torque converter clutch (TCC) remains applied at closed throttle to much lower vehicle speeds to significantly improve the effect of engine braking.
* During acceleration, the TCC is applied in 2nd range and remains applied in 3rd, 4th, and 5th. This improves the drivetrain efficiency and significantly lowers transmission sump temperature when towing heavy loads. In Normal mode, TCC generally applies only in higher ranges and is dependent on throttle position.

Q. Increasing Engine Power - If I install a kit to increase the engine power, what effect will that have on the transmission?
A. The transmission controls have been highly integrated with the LB7 and LLY Duramax diesels and L18 gas engines in GM pickups. Part of this integration is that the TCM has a 'map' of each engine's torque output throughout its operating RPM. The TCM uses 'Shift Energy Management' (SEM). During most range shifts, there is more power available than necessary to maintain acceleration. The unused engine power traditionally goes into slipping clutches, and results in additional heat without adding to vehicle performance. Through engine/transmission communication, SEM is the electronic control process that reduces torque during range upshifts to a level resulting in consistent transmission output torque before and after the shift. The net result is optimized shift quality as well as reduced clutch energy.

Needless to say, when engine torque is increased significantly via various after-market methods, these features are greatly compromised. As with any mechanical system, there is a limit to the level of torque/power that the transmission can handle. Pumping excessive amounts of torque into the transmission will result in excessive heat, gear and bearing loads, and clutch energy absorption.

Q. Shift Delay - Why does my transmission seem to "hang" or delay upshifts when cold? (Diesel powered trucks only)
A. On diesel powered trucks, the Allison transmission has a feature to shorten engine / cab warm-up times. This feature is called Heater Performance Mode. This feature raises part throttle upshift points (2-3, 3-4, 4-5) to increase engine speed when cold weather conditions are detected. In addition, the torque converter clutch (TCC) will not apply below a transmission sump temperature of 31°C/88°F. This also aids in warming the cab more quickly. Under these conditions, it is normal to experience upshifts that seem to "hang" or be delayed.
Back To Top

Q. Shift Stabilization - How/when does it work?
A. Shift stabilization is a software feature in the Transmission Control Module (TCM) that is intended to minimize 'shift busyness', or 'hunting' between ranges. Based on several inputs and a 'map' of engine torque at various RPM and throttle position, the TCM determines before making an upshift whether the engine will be able to maintain vehicle speed in the next higher range. If it senses that it does not, it will prevent the upshift from occurring.

Derek


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## Rowski (Oct 24, 2005)

Double post...


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