I just got my truck yesterday but bought it for hauling my travel trailer. Now I know it is overkill. My trailer is 20' and probably 7,000 pounds loaded.

My question is the TH mode. I would guess that I would normally drive in D (regular overdrive) but I do go up and down a 6% grade when camping in our favorite spot. This is why I got the truck. My 1991 GMC 3/4 ton would only go 25 mph up this grade with the trailer.

I am fairly new to towing (only 10 trips or so) but totally new to the diesel.

Can you put the TH mode on in D? Or, is it only in the Manual mode. The dealer kept saying I could shift manually but I didn't know what he was talking about and would rather find out in a forum such as this anyhow.

Thanks very much,
Ellie

I have a 2006 Silverado duramax with the Allison Transmission.

when you are pulling a trailer or hauling a load put it in tow haul mode

and you can do it with the shifter in D the tranny will then help you slow down by down shifting on its own...

and you can do it with the shifter in D the tranny will then help you slow down by down shifting on its own...

x2

I've occasionally towed 12-13k pounds and I just stick in t/h mode toss it in D and go.

Moved to Allison OEM. Not an engine specific thread! ;)

Thanks for moving this to where it goes.

Thank you for the replies. That makes sense. The salesman had me confused with his telling me to shift in manual.

My old truck manual said not to tow in overdrive so I needed to make sure with this one. I don't have a manual yet.

Ellie

You can shift it yourself using the buttons on the stalk, if you choose to. If you want to hold a gear going downhill or something like that. But with the Tow/Haul mode engaged and the transmission in Drive, you are good to go. When you press the brakes going downhill it will automatically downshift to help slow you down. It works very well. Just remember to hit the Tow/Haul button everytime you turn the truck back on; it goes off when you turn the truck off.

Thanks, Glock. I can remember that because of the little light. I have a prodigy brake controller from my other truck that was installed Saturday. That, and this fantastic truck should take me and trailer down that 6% grade with no problems.

Ellie

If you go down a steep hill with your truck, try out the button. Engage it and tap on the brakes. My uncle frequently used it as sort of an engine brake on his truck.

I pull a 21 foot travel trailer; maybe 6000 lbs, plus some misc gear in the truck bed. Our loads would be similar, I expect.

Run it with T/H on, and you'll hardly know it's back there! Manual shifting is OK, but I find it's a bit redundant; the Allison will do everything you need it to.

I don't remember where I saw it, but I'll quote another member, "It's smarter than you are."

If you want to turn off overdrive you need to hold the T/H button in and then a D with a line through it will come up next to the T/H icon.

Thats for my truck at least.

If you want to turn off overdrive you need to hold the T/H button in and then a D with a line through it will come up next to the T/H icon.

Thats for my truck at least.

:exactly: I dont think That happens on the 6 speeds

drive, tow/haul on, leave it alone.

:exactly: I dont think That happens on the 6 speeds

Correct. It doesn't.

Thanks guys. I am towing the trailer this Friday because I can't wait to try it out. I will simply engage the TH whenever I drive whether on the freeway or on the steep grades.

I really appreciate the help.

Ellie

drive, tow/haul on, leave it alone.
:exactly:

The only time I shifted manually was coming out of Yellowstone towing a 17k fiver. It was snowing and I was going through Sylvan pass. I put it in first gear and creeped down the hill. Other than that, the truck is always in D and if I am towing, the TH mode is on.

Well, I am in the campground... towed today and put her in TH mode all the way. It is great, even changes gears going down grades and I don't use the brake as much. My 1991 GMC really tried but could only go 25mph on the 6% grade. Today, for the first time I went 55 and that was great!

Love this truck. Thanks for the advice. It helped.

Ellie

When I tow my tt my tranny temps stay lower in t/h mode than when empty and in d.

I don't remember where I saw it, but I'll quote another member, "It's smarter than you are."
THAT WAS ME :D:D or at least i said it once

THAT WAS ME :D:D or at least i said it once


You're a wise man!

x2 t/h and forget it keeps the tranney temp down i to a 5th wheel 13k no t/h temp climbs in t/h temp drops

x3 on much lower tranny temp w tow/haul on. what a great feature.

I regularly drive into a city with a pretty good downhill grade, and I turn right at the bottom of the grade. Even when empty I will hit the T/H button as I am cruising down the hill and the truck will begin to downshift more aggressively, which requires a lot less braking. Of course, I use it full time when towing my 11,000lb fiver.

T/H is a good thing! using it when not towing - or when towing very little - shouldn't harm anything - it only changes the shift pattern to make it more aggressive, but higher revving. Hence the lower tranny temps. At highway speeds (over 80km/h - 50mph), it won't make any difference (on the five speeds that is).

Enjoy your truck! The grin can be kinda hard to wipe off your face when you start drivin these.