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.

[Redsky]

With GM the recommendation is to use it whenever the payload is at 25% of the rating or more. It is the payload that affects the transmission and the Tow Haul mode is designed to protect the transmission and prolong its life.

Use of Tow Haul mode will increase the effect of the exhaust brake in slowing the truck on downgrades as an additional benefit.

[Turtle_n_Peeps]

chevor wrote:

n7bsn wrote:
I would suggest you read the manual, they are actually quite clear about when they recommend to use it

But no, they don't help MPG, for example, down hill they can force the vehicle into a lower gear (engine braking) which consumes more fuel

How do you consume more fuel downhill in a lower gear?

I use mine under 50 mph pulling and when slowing down empty and pulling. I like to be in overdrive gears as fast as possible.

I have the answer for that, at least in my case.

I only tow about 7K so I'm WAY under gross for my truck. When I have TH on when descending hills I may want to go down the hill at lets say 60 MPH. If I tap my brake, even for an instant, it will downshift and put the turbo into full retard which takes me from 60 MPH to 50+. Then if I tap my brake again it will take me to 40. Then I have to "add fuel" to take me up to 60 again.

I get to 60 MPH and then I have to tap my brake for a tiny curve in the road and then the whole thing starts over again. if this happens a few dozen times it gets super annoying and adds quite a bit to fuel costs not to mention the tranny gets shifter a whole lot more.

OP if you're looking for fuel mileage TH is not the way to do this. In your manual it will state the recommendation of when GM "recommends" you use this feature. I'm under the weight of recommendation so most of the time it's off on my truck even, while towing.

[hbensley]

I read it on here before and since then have followed this advice; "Whenever I haul or tow something, the tow/haul button is used."
Before I read this I too was wondering if I had enough cargo or weight in the truck to engage the option. There's no guessing anymore.

[wilber1]

Anything that delays upshifts isn't helping mileage.

[BenK]

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

[shakyjay]

The tow/haul button is meant to be used when towing or hauling just exactly as the name implies. I use it at all times when towing my tt. The Allison seems to like it, runs a little cooler. On downhill runs if you just tap the brake once the trans does a fantastic job of holding that speed from that point on.

When I use truck to haul a load I generally do not use it. Usually when I am hauling it is on flat ground with loads that are not too heavy. If I do load it to the max and have to negotiate any grades then yes the tow/haul gets used.

I think you just need to play around with it and find out when it feels right to you.

[Vet_Man]

With a 35ft MH with toad, I like the feel speeding up and slowing. When the toad is on I am in Tow/Haul Mode. See no real difference in gas mileage, but I knew it was not an Economy car when I bought it. I have a V/10 Gas engine.

[pappcam]

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.

[Old-Biscuit]

Just push the dang button and see how it reacts!

It will change the shift points.....stay in each gear longer before up shifting so that you can accelerate better when towing (trailer) or hauling (load in bed of truck)

It will downshift when decelerating adding some transmission braking.

It will actually lower mpg (slightly) due to longer shift points.

I use it when towing and non-towing in city stop/go traffic.

Can be selected at any speed.

PUSH the button......:B

[2-MTnesters]

n7bsn wrote:
I would suggest you read the manual, they are actually quite clear about when they recommend to use it

But no, they don't help MPG, for example, down hill they can force the vehicle into a lower gear (engine braking) which consumes more fuel

In a modern vehicle the engine enters an 'over-run' state. That is, it is moving the engine & NOT the engine moving the car. NO fuel is used. Anybody with a fuel computer that gives an instant display can see that fuel use drops to nil. BUT, as soon as the forward speed & engine/gear is matched it will start to consume fuel. This applies to both gas & diesel engines.
In the gas variant the spark plugs continue to fire to burn off any residual fuel to prevent cat damage, but no new fuel is added. This is why it is MORE efficient to engine brake and keep the vehicle in gear while going down hills than use the foot brake (risk of overheating on long descents) or coast in neutral (uses fuel to idle).

[chevor]

n7bsn wrote:
I would suggest you read the manual, they are actually quite clear about when they recommend to use it

But no, they don't help MPG, for example, down hill they can force the vehicle into a lower gear (engine braking) which consumes more fuel

How do you consume more fuel downhill in a lower gear?

I use mine under 50 mph pulling and when slowing down empty and pulling. I like to be in overdrive gears as fast as possible.

[kaydeejay]

n7bsn wrote:
But no, they don't help MPG, for example, down hill they can force the vehicle into a lower gear (engine braking) which consumes more fuel

Er, not quite! When the engine is braking the fuel is cut off, ie NO fuel is being used at that point.
But in general I agree that Tow/Haul will not improve mpg, but it will help the transmission stay cooler.

[FishOnOne]

When towing the travel trailer or large cattle trailer I use the tow/ haul mode, but when towing the boat or utility trailer with tractor I don't use it. It seams that I can make better fuel economy when not using the tow/haul mode.

[downtheroad]

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.

[n7bsn]

I would suggest you read the manual, they are actually quite clear about when they recommend to use it

But no, they don't help MPG, for example, down hill they can force the vehicle into a lower gear (engine braking) which consumes more fuel