Tow/haul mode always when towing?

[mtjag]

I have a new to me 2019 1500 5.7 hemi eTorque with the 3.92 rear gear ratio and will pull a loaded 5800# travel trailer. I think this truck will pull this trailer with ease on flat ground. My question is should I always pull in tow/haul mode or just when I'm in mountains up or down? I understand the tow/haul mode disables the cylinder deactivation so that may be one reason to leave it in tow/haul mode. I'm just thinking of trying to maximize fuel economy, but not at the risk of tearing the torque converter or tranny.

 

[SpeedyV]

If you’re running level ground, temps are good, and you’re pulling easy, I can’t imagine needing to stay in Tow/Haul. It’s always there if you find the truck shifting frequently or heating up.

 

[SD Rebel]

The big thing Tow/Haul mode also does is when you are slowing down, it will downshift to a lower gear, and will downshift even lower the harder you brake. It will then hold that lower gear, even when coasting. It won't upshift again until you press on the accelerator. Highly recommend you use tow haul mode for that reason in those conditions.

You will of course not have MDS in operation in tow/haul mode, which will slightly lower your mpg when on level easy throttle, as will the transmission taking longer to shift up, to aid a bit with acceleration.

But it's not like you can't toggle the switch off/on whenever you like. If you are going up or down a steep hill, switch it on, if you are cruising on a flat road, switch it off if you want the MDS to turn on.

Just keep an eye on the tranny temps. The manual actually recommends you go into tow/haul mode on mountain roads even without towing in order to help keep trans temps cooler.

 

[Trooper4]

Never use it when the going is easy. Low hills and minor downgrades aren't a problem. I have the 5.7 3.92 setup also, and rarely use tow/haul, but like everyone says, watch the temps as a guideline.

 

[Rick3478]

You chose the 3.92 gears, which will reduce the torque load on the transmission and driveshaft, so good move on your part for planned towing. I made the same choice for similar reasons. As @SD Rebel said, tow/haul mode alters the transmission shift points, and is probably a good choice for hilly areas. I would add that regardless of mode, sixth gear is direct drive in the transmission, using none of the planetary gear sets, so almost no wear or heat is caused. This is the gear you would like to be in for steep pulls, if at all possible. I wouldn't worry about the torque converter, as it locks up at pretty low speed under most conditions, so won't be getting hot. Travel trailers, for the most part, are not very aerodynamic, and I'd be surprised to see MDS kick in on level stretches at highway speed. Downhill, sure, let it go ECO if it wants to. I'll be looking to use my tow/haul and steering wheel ERS buttons to get desired performance. Also, I'm considering an aftermarket finned rear differential cover to help keep the gears cool. And here's words you don't see on here often - slow down a bit. 55 is still legal on most highways and if people want to pass, they'll figure it out. And stop once in awhile to let things cool down. Lots of main roads have designated places where the big trucks pull off to cool their brakes, check tires, etc. You can do likewise.

 

[Curlymurt]

I pretty much always use it with the travel trailer that's about the same weight. With that said, I don't really notice a difference of I forget to turn it on our not. If I'm towing a utility trailer trailer, I don't use it until I start to get a reasonable amount of weight. Then it actually feels better to drive with it on because of the shorter shifts.

 

[HSKR R/T]

There won't be any significant difference in fuel mileage, when towing, between tow/haul on or off. Using it will only benefit you. That's why it's there.

 

[SpeedyV]

The big thing Tow/Haul mode also does is when you are slowing down, it will downshift to a lower gear, and will downshift even lower the harder you brake. It will then hold that lower gear, even when coasting. It won't upshift again until you press on the accelerator.

The manual actually recommends you go into tow/haul mode on mountain roads even without towing in order to help keep trans temps cooler.

Great point. There’s a large river valley heading down to a traffic light where I’ll use Tow/Haul (while unloaded) just to avoid riding the brake for 60+ seconds. I’ve learned to force additional downshifts by tapping my brakes a few times. It’s pretty slick. And it’s absolutely necessary if pulling a heavy load.

 

[Darksteel165]

Great point. There’s a large river valley heading down to a traffic light where I’ll use Tow/Haul (while unloaded) just to avoid riding the brake for 60+ seconds. I’ve learned to force additional downshifts by tapping my brakes a few times. It’s pretty slick. And it’s absolutely necessary if pulling a heavy load.

You can just use your gear selector to downshift if you want. Tow mode or no tow mode.

 

[silver billet]

Yes, always use it when towing >5000 pounds, that's what it's there for. It saves your transmission and your brakes.

You'll never hit MDS with that kind of load, even with TH disabled. The engine simply cannot make enough torque with 4 cylinders pulling that kind of load. On the flats you'll probably be sitting mostly in 7th, with a fair amount of time in 8th, but personally for that load I'd gear limit to 7th.

 

[SpeedyV]

You can just use your gear selector to downshift if you want. Tow mode or no tow mode.

Too many clicks to get down to 4th and back up again…although I wouldn’t have to reach as far. First-world dilemma

 

[JF19Longhorn]

I always just turn it on and forget about it.

Only other thing I might do is lockout 8th.

 

[Darksteel165]

Too many clicks to get down to 4th and back up again…although I wouldn’t have to reach as far. First-world dilemma

You can use both.
Keep the truck in towmode and gear selected to 8th then just downshift when you want to use grade braking manually.

It is more work but can be very useful especially going downhills.

 

[Richard320]

Try it both ways and do what feels right. Watch the temperatures now so you'll know when towing if things are just high normal or if they're too hot.

I use tow/haul all the time when I go up in the hills near me, without a trailer. On the uphill it stops the gear hunting and on the downhill it handles the compression braking for me. And when I get back to town and get on the freeway, it's not a big deal if I forget to undo it the way manual downshifting is.

 

[Trooper4]

You chose the 3.92 gears, which will reduce the torque load on the transmission and driveshaft, so good move on your part for planned towing. I made the same choice for similar reasons. As @SD Rebel said, tow/haul mode alters the transmission shift points, and is probably a good choice for hilly areas. I would add that regardless of mode, sixth gear is direct drive in the transmission, using none of the planetary gear sets, so almost no wear or heat is caused. This is the gear you would like to be in for steep pulls, if at all possible. I wouldn't worry about the torque converter, as it locks up at pretty low speed under most conditions, so won't be getting hot. Travel trailers, for the most part, are not very aerodynamic, and I'd be surprised to see MDS kick in on level stretches at highway speed. Downhill, sure, let it go ECO if it wants to. I'll be looking to use my tow/haul and steering wheel ERS buttons to get desired performance. Also, I'm considering an aftermarket finned rear differential cover to help keep the gears cool. And here's words you don't see on here often - slow down a bit. 55 is still legal on most highways and if people want to pass, they'll figure it out. And stop once in awhile to let things cool down. Lots of main roads have designated places where the big trucks pull off to cool their brakes, check tires, etc. You can do likewise.

Agreed. I run 55-65 when towing. Unless passing I never go above 65. I very rarely see the ECO light, and then only on level with either no wind or tailwind.

 

[Trooper4]

Yes, always use it when towing >5000 pounds, that's what it's there for. It saves your transmission and your brakes.

You'll never hit MDS with that kind of load, even with TH disabled. The engine simply cannot make enough torque with 4 cylinders pulling that kind of load. On the flats you'll probably be sitting mostly in 7th, with a fair amount of time in 8th, but personally for that load I'd gear limit to 7th.

I get 8th quite often on the level. This is in the Sacramento area on the way to Palm Springs. But I was going South, so it was a downhill run.

 

[silver billet]

I get 8th quite often on the level. This is in the Sacramento area on the way to Palm Springs. But I was going South, so it was a downhill run.

My truck will pull on the flats in 7th quite often; not just down hill, but flat with even minor upwards slope. I have the 3.21 so I expect your 3.92 to be the same way for the same load, except you'd be in 8th instead.

I'm pulling a somewhat heavier load than OP, but with the 3.21. My preference is to tow in 6th at about 2200 to 2300 RPMs. The truck will do 7th (your 8th) at 1800-ish but I just find there is less power there, more downshifting, and I suspect its easier on the engine to tow at higher RPMs.

 

[HEMIJAKE]

Depends on what I'm towing. My 1000# side by side, rarely unless on hilly roads. My 5,000# camper, always. I think it just makes it easier on the truck to get going, and to stop more efficiently. I'm all about minimizing wear and tear when I can.

 

[mtjag]

Thanks to all for your insight as I do appreciate the experience you've shared with your respected Rams. I'm an older guy so towing between 55-65 for me is my happy place. I try to avoid interstates when possible as I like 4 lane state roads best. We live at 8500' elevation and anyway I leave our property is going to be up or down by a 7% grade or more. My old TV was an 05 Sierra quadrasteer with the 6.0l V8, but it didn't have the horses or the torque the Ram now has. My current mpg without having towed yet is 18.6mpg. I suspect that will be cut in half which would be just about the same as my old 05 Sierra with a four speed tranny. Maybe I'll be over 10mpg which would be a win in my book.

 

[HEMIJAKE]

Thanks to all for your insight as I do appreciate the experience you've shared with your respected Rams. I'm an older guy so towing between 55-65 for me is my happy place. I try to avoid interstates when possible as I like 4 lane state roads best. We live at 8500' elevation and anyway I leave our property is going to be up or down by a 7% grade or more. My old TV was an 05 Sierra quadrasteer with the 6.0l V8, but it didn't have the horses or the torque the Ram now has. My current mpg without having towed yet is 18.6mpg. I suspect that will be cut in half which would be just about the same as my old 05 Sierra with a four speed tranny. Maybe I'll be over 10mpg which would be a win in my book.

I don't pull hard and fast either. With my 3.21 and 5,000# camper, I can average around 12-13 mpg. Taking it easy of course. So you're probably in the ballpark. Since then, I've added a level and 35's, so I expect my mpg to go down considerably this year.