Duramax, Allison, Tow-Haul mode advice

[Second_Chance]

We traded the '05 Tahoe in on a new 2013 GMC Sierra 2500HD crew cab with the Durmax diesel, Allison transmission, and HD tow package. We tow a Surveyor Sport 220 that weighs in about 4,400# dry with about 2,300# cargo capacity (which we never approach). For those of you with similar GMC/Chevy trucks, in what load/grade combinations do you or do you not use the Tow-Haul mode? Do you wait until the motor is working harder or just use it all the time when towing. I realize our travel trailer is nowhere near the limit for the truck, but want to strike a balance between economy and vehicle life...

[jevanb]

I also like TH on because the convertor is locked above 2nd, but since the lock-up box is going in I will not have to drive around town with it on , because you never know when someone wants a race...lol

[kaydeejay]

Turtle n Peeps wrote:
Without writing a book, in my case, it conserves too much energy. IOW's, when I come down a mountain I may tap my brakes several times and each time I do it downshifts. Then I have to add fuel to keep up with the turtles. Then it downshifts again and I add more fuel...................Downshift, fuel, downshift, fuel, downshift, fuel, downshift, fuel........That adds up.

Sounds like the perfect time to switch to manual mode for gear selection!

[Turtle_n_Peeps]

kaydeejay wrote:

fly-boy wrote:
I would not bother with T/H for a 4400 pound trailer. All it is going to do is decrease your fuel economy.

Please explain why you think that. Higher shift points does not necessarily equate to worse fuel economy if the power being transferred to the road is the same. The engine may be revving higher but at a lower throttle opening.
I have noticed NO difference between T/H on or off as far as economy is concerned.
In fact theoretically economy could be a tad better due to the lack of heat lost in the torque converter.

Without writing a book, in my case, it conserves too much energy. IOW's, when I come down a mountain I may tap my brakes several times and each time I do it downshifts. Then I have to add fuel to keep up with the turtles. Then it downshifts again and I add more fuel...................Downshift, fuel, downshift, fuel, downshift, fuel, downshift, fuel........That adds up.

[just_me]

Use of the EXHAUST brake is recommended to use often, to keep it moving freely, and the other thing is to save the service brakes.

[gscudder]

If theres something on the Ball it's in Tow-Haul!!

[kaydeejay]

fly-boy wrote:
I would not bother with T/H for a 4400 pound trailer. All it is going to do is decrease your fuel economy.

Please explain why you think that. Higher shift points does not necessarily equate to worse fuel economy if the power being transferred to the road is the same. The engine may be revving higher but at a lower throttle opening.
I have noticed NO difference between T/H on or off as far as economy is concerned.
In fact theoretically economy could be a tad better due to the lack of heat lost in the torque converter.

[M_GO_BLUE1]

When I'm towing the tow-haul button is always on...

[fly-boy]

I would not bother with T/H for a 4400 pound trailer. All it is going to do is decrease your fuel economy.

[freewayrandy]

timdan94 wrote:

sayoung wrote:

salem wrote:
I put mine in TH when I'm sitting in my driveway getting ready to take off and leave it in till I unhook.

Same here on my 12 but I am towing close to 14k.
Exhaust brake only works when in tow/haul.

exhaust brake does work without tow haul activated. its just not as aggressive. I use the exhaust brake in everyday driving.

X2 with Banks brake

[timdan94]

sayoung wrote:

salem wrote:
I put mine in TH when I'm sitting in my driveway getting ready to take off and leave it in till I unhook.

Same here on my 12 but I am towing close to 14k.
Exhaust brake only works when in tow/haul.

exhaust brake does work without tow haul activated. its just not as aggressive. I use the exhaust brake in everyday driving.

[Second_Chance]

Thanks, everyone - very helpful. It seems the majority consensus is to default to T/H mode whenever towing.

[jalichty]

I would recommend you use the T/H mode all the time you tow and, as well, simply push the button for the engine braking system to operate. The engine braking system will help a lot when going down mountain passes, or really steep hills, and will allow you to not use the brakes as much. We have a 2012 GMC 2500HD D/A combo and the T/H and engine brake system work great when we are pulling our FW and boat, with a total combined weight of around 12,000.

[jevanb]

sayoung wrote:

salem wrote:
I put mine in TH when I'm sitting in my driveway getting ready to take off and leave it in till I unhook.

Same here on my 12 but I am towing close to 14k.
Exhaust brake only works when in tow/haul.

same here but I am sitting at 20k combined while towing, and yes I do have a exhaust brake via..EFI live

[Turtle_n_Peeps]

nevadanick wrote:
I pull quite a bit more than that and only use tow haul when i get in mountains.

x2. And even then I find it annoying in the mountains sometimes. I will tap the brakes and it will down shift and then I add fuel and it will upshift and then I will tap my brakes and it will downshift............I also get slightly better fuel mileage with it off.