Tow haul button

[Hardcandy]

I have a 04.5 duramax 3500 and I'm not sure when to use the tow/haul button on my gear shift also using this will it help my MPG? Thanks.

[JustLabs]

I never use the T/H on my truck. My fifth wheel is 11,000lbs and its just not needed IMO.

It raises the shift points and makes the truck stay in each gear longer than needed.

There is zero difference in trans temp while using it or not.

[captnjack]

The owner's manual for my 2002 2500 Suburban with 8.1 liter recommends using tow/haul when towing 75% or more of GCWR.

I just finished a trip during which I was under the impression that tow/haul should be on whenever towing, regardless of weight. I tow a Hybrid Roo 233S at a weight I believe is around 5500 lbs loaded (ballpark anyway). At one point I forgot to engage tow/haul mode. I didn't notice for about 20 minutes or so. Maybe more. I didn't notice any change in driving or handling. Engine temp and tranny temp both stayed low. I began to experiment. The shift points were stretched out a little in tow/haul. I noticed that at 55 MPH I'd be at 2300 RPM in tow/haul and 1800 w/o tow/haul. Seems that for me, tow/haul is doing nothing but wasting gas. Although there were no steep hills involved; I guess that could change things a little.

Seems like cruise control is fine until you hit hills. My guess is that 50 MPH up the hill and 60 MPH down the hill works out to same average speed but uses less fuel.

Thoughts anyone?

[wilber1]

There is no real manual mode on these transmissions. All they do is limit the top gear the transmission uses. They still shift automatically up to that gear. If selected, the tow haul program is still functioning even with the transmission in "manual" mode.

[Dannyabear1]

Tom_Diane wrote:

BenK wrote:
The Tow/Haul button/function was invented for those who do NOT know HOW2 manage
their automatics by manually shifting....to do down a gear or more...to hold a
gear longer, etc

Pretty soon the OEMs will increase the cost/price and complexity to manage folks
who will NOT and/or do NOT understand HOW2 use the Tow/Haul button.

My guess is electrical. Strain gauge and/or when the trailer plug has
a connection. The TV will then automatically switch on the Tow/Haul function for
the Automatic transmission

Who ever told you that? The tow/haul was designed so that you don't have to manage the automatic as much. The way you phrased it is pretty demeaning! That's like saying that automatics "were invented" for people who don't know how to manage a manual transmission. Even with the TOW/HAUL on, you still have to manage the transmission! Let me guess, you jumped right in and knew exactly how it works and how to use it and you came up with this conclusion? The op asked a question and he got some good answers except when you need to feel good about yourself, you throw that language in there. This site is supposed to be for help and ideas, advice etc. Sorry all but it gets old having to read replies to post such as those that are demeaning to others because someone had a question that seems simple to others! To the op, a rule of thumb is that anytime you hook a trailer up or put 2 or 300 lbs or more in the box, push the tow haul on. Changes your shift point, less strain on tranny.

So, you use tow/haul when you take family get groceries?

[BenK]

Keith, I do know more, but both my eng short hand and why I don't come
by as often...

FWIW...my consulting team worked on the, then, next gen hybrid and the
automatic redesign. We were called in late, as they were having thermal problems

Found that they wanted the controller inside the automatic and use the
ATF as coolant :E

Talked shop with several of their tranny guys and did cover T/H. So,
yes understand 'their' genesis for the T/H function (warranty) and
most of the stuff it does (PSI is only one aspect). They did NOT want
to have two electric motors, but space was at a premium...boy is that
automatic going to be pricey to fix...

Ordered the 'F60' option when ordering my Suburban. For those who
don't know...the F60 option is the snow plow prep package and begets
the 1 ton front torsion bars, etc.

Since my rear diff assembly is 'almost' identical to the 1 ton dually
of that year (the difference is in the brakes...cylinders are larger
bore and the MC has larger bores, proportioning valve is different, etc)

Tongue on cheek call mine a K3500...

Turtle is an old salt and knows his stuff. He has more patience than
I, as I'd rather have been able to order mine with manual 5 speed.

What bothers him is the kind of stuff I dislike about automatics
and the 'new' bells and whistles for the non-manual owners...

[Tystevens]

BenK wrote:
The Tow/Haul button/function was invented for those who do NOT know HOW2 manage
their automatics by manually shifting....to do down a gear or more...to hold a
gear longer, etc

Pretty soon the OEMs will increase the cost/price and complexity to manage folks
who will NOT and/or do NOT understand HOW2 use the Tow/Haul button.

My guess is electrical. Strain gauge and/or when the trailer plug has
a connection. The TV will then automatically switch on the Tow/Haul function for
the Automatic transmission

Not exactly true for most any vehicle sold this century. On the Allison transmission, for example, T/H will cause the torque converter to lock in 2nd gear (it locks in 4th or 45 mph in 'regular' mode), helping keep temps down when you're towing in stop and go traffic or climbing slow in the mountains. Really works. Also causes the grade braking to come into play, increases pressures in the transmission to afford quicker shifts, and a few other ideas that both improve performance when towing and help preserve your transmission. You can't do any of this by manually shifting.

My T/H is on whenever a trailer is hooked up. I even use it unloaded when driving 2-lane twisty roads up in the mountains.

[2-MTnesters]

Not sure why BenK is commenting on Tow/haul button anyway if he tows with the vehicle in his sig. They didn't even have this option on that model. I really don't understand how a 3/4 ton suburban can also be a K3500....... though 3500 was 1 ton. Also don't think I'd call a 1998 Mazda B2500 a 1/2 ton P/U, more like a Ranger which is not even close to a 1/2 ton.

[Vet_Man]

BenK why do you have an automatic if you want to shift? Give the guy a break, he was looking for help not critics.

[kaydeejay]

BenK wrote:
The Tow/Haul button/function was invented for those who do NOT know HOW2 manage
their automatics by manually shifting....to do down a gear or more...to hold a
gear longer, etc

Pretty soon the OEMs will increase the cost/price and complexity to manage folks
who will NOT and/or do NOT understand HOW2 use the Tow/Haul button.

My guess is electrical. Strain gauge and/or when the trailer plug has
a connection. The TV will then automatically switch on the Tow/Haul function for
the Automatic transmission

Sorry Ben, but I had given you credit for knowing more than that. That comment comes across as almost insulting, which is not your usual style.
T/H is NOT simply a substitute for manual shifting. It does raise the shift points, but it also engages the torque converter clutch in the lower gears as well, This is what reduces the slippage and contributes to keeping trans temps down.
It then times the downshifts under braking to maximize the engine braking effect, while also assisting cruise control to maintain a steady speed within the capabilities of the system.
But back to your observation - even if that was all it did, it removes one more task from the driver. Is that a such bad thing?

[Hardcandy]

Tom_Diane wrote:

BenK wrote:
The Tow/Haul button/function was invented for those who do NOT know HOW2 manage
their automatics by manually shifting....to do down a gear or more...to hold a
gear longer, etc

Pretty soon the OEMs will increase the cost/price and complexity to manage folks
who will NOT and/or do NOT understand HOW2 use the Tow/Haul button.

My guess is electrical. Strain gauge and/or when the trailer plug has
a connection. The TV will then automatically switch on the Tow/Haul function for
the Automatic transmission

Who ever told you that? The tow/haul was designed so that you don't have to manage the automatic as much. The way you phrased it is pretty demeaning! That's like saying that automatics "were invented" for people who don't know how to manage a manual transmission. Even with the TOW/HAUL on, you still have to manage the transmission! Let me guess, you jumped right in and knew exactly how it works and how to use it and you came up with this conclusion? The op asked a question and he got some good answers except when you need to feel good about yourself, you throw that language in there. This site is supposed to be for help and ideas, advice etc. Sorry all but it gets old having to read replies to post such as those that are demeaning to others because someone had a question that seems simple to others! To the op, a rule of thumb is that anytime you hook a trailer up or put 2 or 300 lbs or more in the box, push the tow haul on. Changes your shift point, less strain on tranny.

Thank you so much for your input. Some people are just rude and make one not want to ask any questions, I thought that was what this and any other fourm was about people with like interest to come together and share info with each other.

[Tom_Diane]

BenK wrote:
The Tow/Haul button/function was invented for those who do NOT know HOW2 manage
their automatics by manually shifting....to do down a gear or more...to hold a
gear longer, etc

Pretty soon the OEMs will increase the cost/price and complexity to manage folks
who will NOT and/or do NOT understand HOW2 use the Tow/Haul button.

My guess is electrical. Strain gauge and/or when the trailer plug has
a connection. The TV will then automatically switch on the Tow/Haul function for
the Automatic transmission

Who ever told you that? The tow/haul was designed so that you don't have to manage the automatic as much. The way you phrased it is pretty demeaning! That's like saying that automatics "were invented" for people who don't know how to manage a manual transmission. Even with the TOW/HAUL on, you still have to manage the transmission! Let me guess, you jumped right in and knew exactly how it works and how to use it and you came up with this conclusion? The op asked a question and he got some good answers except when you need to feel good about yourself, you throw that language in there. This site is supposed to be for help and ideas, advice etc. Sorry all but it gets old having to read replies to post such as those that are demeaning to others because someone had a question that seems simple to others! To the op, a rule of thumb is that anytime you hook a trailer up or put 2 or 300 lbs or more in the box, push the tow haul on. Changes your shift point, less strain on tranny.

[campigloo]

Tow/Haul raises line pressure in the tranny, takes the car like slip out of the torque converter, making it shift quickly, and locks it in giving it a more direct drive much like a standard tranny. This is where you get heat reduction. It has nothing to do with knowing when to up or down shift an auto tran.

[AUWing]

Trailer connected - Tow/Haul light . Toss the K&N for a real filter

[Hardcandy]

downtheroad wrote:
I just find this to be an interesting question...with all the mods on your truck and fire power inside your rig that you list in your signature and you are asking about the function of the basic 'tow haul' feature...
Go figure.???

But, yes. Use the tow haul when you are towing. It changes the shift points, keeps the tranny cooler, and engages grade braking.

RV'ing...forget about mileage.

SORRY I didn't mention that the truck was bought the way I is. And I just happen to like fire arms and believe in my right to carry if I choose to.

[Mvander]

pappcam wrote:
You should probably use the tow/haul button when you tow/haul something. Also you might want to put the transmission in D when you want to move forward.

Select "R" to race:B And "P" to pass!!!