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Do I really NEED to use tow haul on highway ?

Ktm2smoker

Ktm2smoker

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With a 9000 lb 31 foot camper, my HO 3500 dually crew tows my trailer camper around the PA hills and highways like it's not even there. A dream realized. Love the auto exhaust brake and tow haul shifting around town and in the steep back hills. But with tow haul on the highway (exhaust brake off) it just seems to be killing my fuel economy, refuses to coast, seems to drag when I'd rather be coasting downhill. Does this mode adjust line pressures or anything like that or just shift points? At 65 mph most uphills don't even result in a downshift. Will I hurt the Aisin if I'm not in townl haul with this 'tiny' camper?

I got 11.5 mpg round trip, only 1300 miles on truck so far.....first diesel.

Rich
 
I’ve NEVER used the tow / haul mode on any of my tow vehicles from 1996 to my 2022 Ram 3500.! And we are based
out of the NORTH EAST.,!., Where UP HILL BOTH DIRECTIONS IS COMMON.
If you wind up doing hundreds of miles in downtown traffic I’d say hit the button, other than that we leave
It off, hit the highway and set the cruise at 68 and just idle down the road. BUT, REMEMBER, That’s my
OPINION.
 
I always leave it on because I live in a pretty mountainous area and like the aggressive shift points but you definitely don't need to leave it on and won't damage anything by towing without it.
 
I only got 6 gears in my Aisin and it seems over 60 mph almost nothing kicks it down but perty steep uphills. And then it's one gear with an increase in RPM from 1900 to 2200ish. No more WAAAAAAAA like my 6.2 F250 gasser would do:). on this truck, it just seems like the converter stays locked up so if I'm not giving some go-pedal it'll lose speed or, at the least, not pick up speed downhill. It could very well be the wind resistance on my TT but when I had my F250 gasser it would definitely pick up speed on the highway downhills in upper PA.

Overall, the increase in mpg from 7.9 to 11.5 on this trip to Kneobels that I've been doing for decades, and at an increased speed, is all I was hoping for. The increase in towing experience from white knuckle all the way to 'honey, is there a trailer back there' is phenomenal. And with the 50 gallon tank my 280 mile round trip only took me down to a half tank and that is worth the price of admission with all the small gas stations in rural PA !

Sorry to rant, just loving my new girl, Megalodon. She goes by 'Meg'........

Back to the discussion...to tow/haul or not to tow/haul.
 

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Don't need to use TH unless it's hunting for gears.
 
What's Tow Haul?

LOL. My HO only sees TH around town as I like the aggressive EB, and if I'm in steep terrain pulling my 16K setup in sig.
 
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That was my feeling, my concern is... ..I guess was..... transmission management outside of shifting. Line pressures, torque converter lockup issues, that sort of thing.
 
I use it anytime I have a trailer on the back. Around town is where I notice it the most, when its turned off the truck seems to lug..... pulls fine without it but definitely lugging. On the highway it does not make a difference, once the Cummins is up to speed it will stay in 6th gear unless you are climbing a really steep grade. Gassers have to downshift while the diesels rely on the turbo for "ALL THE BOOST".
 
MEGA HO 3500 said:
Don't need to use TH unless it's hunting for gears.
Click to expand...
Yep, that's exactly what the owners manual says too. If it's not hunting a lot, don't bother. The following is from my 22 owners manual. I bolded the first AND as it's important.
When to Use TOW/HAUL Mode
When driving in hilly areas, towing a trailer, carrying
a heavy load, etc., and frequent transmission
shifting occurs, push the TOW/HAUL switch to
activate TOW/HAUL mode. This will improve
performance and reduce the potential for
transmission overheating or failure due to
excessive shifting.
 
I keep tow haul on anytime i have a trailer or the bed loaded heavy, and when plowing once i hit the main roads and highway it shifts to 6th it wont make a difference on your millage the weight your towing will affect the millage though
 
During the long wait on my order I thought I'd read the 22 owners manual sufficiently, missed that on page 152, 154, 156. It always mentions overheating the tranny as the reason. Got a guage to monitor that. Page 147 notes that having the exhaust brake on with TG will add even more agression to downshifting in TH mode!

To be fair, there's a note on page 226 that recommends always using TH when towing. I'll be playing with it but doubt I'll need it most of the time.
 
Ktm2smoker said:
During the long wait on my order I thought I'd read the 22 owners manual sufficiently, missed that on page 152, 154, 156. It always mentions overheating the tranny as the reason. Got a guage to monitor that. Page 147 notes that having the exhaust brake on with TG will add even more agression to downshifting in TH mode!

To be fair, there's a note on page 226 that recommends always using TH when towing. I'll be playing with it but doubt I'll need it most of the time.
Click to expand...
Like you, I missed that the manual says 2 different things. I saw the recommendation to use TH whenever towing and just went with that. Re-reading it, I see that it says (basically) turn it on if you’re towing and the transmission is frequently shifting gears.

I’m going to test this on my next trip (a few months out). I think I’ll get better mileage without it and I know if I need it I can just flip a switch…
 
Good thread and good info. I didn't catch the conflict in the owners manual either. I haven't read it cover to cover but I've scanned it all for the interesting parts.

I don't mess with TH much either unless I'm loaded heavy. It does just fine without it. I don't really care for the normal shift points, it could build a few more rpm's before shifts but it pulls out of the hole pretty well so....

I've done the TH and the EB and find that it's typically too aggressive for flat land. It starts grabbing gears and feels like I'm standing on the brake. I typically prefer to coast down to stops from at least a half mile away. Throw the TH and EB on and it'll bring a load down nearly to a stop in a couple hundred yards, or at least it seems. When I make it to the mountains with a load the aggressive combo will be very welcome though.

So with average loads I've found that I prefer leaving the TH off and turn the EB on. Just a tickle of throttle will keep the EB off until you're ready for it.

I've not noticed any gear hunting with the Aisin even with a good load in hills. I won't mention weights for fear of being flamed by the weight police but I can tell you I've tested the truck and haven't seen any transmission temp issues. But I will say with heavier loads I flip to TH to get the improved shift points for takeoff.

That's just $.02. That and a couple bucks might get you a cup of coffee.
 
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