Tow haul transmission mode

[Bruce H]

Ok, so does the "tow haul" cause the ecm to adjust the fuel mixture in the engine?

[Raspy]

Originally Posted by Bruce H

Ok, so does the "tow haul" cause the ecm to adjust the fuel mixture in the engine?

No.

[cpaharley2008]

Originally Posted by floyd

What transmission is being used, by code or number?

My 2014 Ram has the 8 speed auto with 3:21 rear, 415 hp/420 torque with CAI

[Cliff Hotchkiss]

Originally Posted by bobblangley

I was told my the service manager at our local RV service shop to NEVER to my trailer unless my transmission is in tow/haul mode. I'd like to tap the collective brain and experience of the group about this.

Apparently, in tow/haul mode, the transmission locks into direct drive so there are fewer moving parts under stress.

I am towing a 1995 Bigfoot 17G trailer (approx wet weight 3000#) with a 2002 Chevrolet HD 2500 diesel pickup that hardly knows the trailer is behind it. I'd like to at least drop into overdrive when cruising on flat ground at 55 - 60 mph but am reluctant to do so based on advice given.

Any thoughts on or experience with this will be much appreciated.

😎 I’ve towed my 5.0TA for 10k miles now. This is my first trailer and bought a brand new 2016 F150 to tow it. It has a 2.7 Ecoboost with 6 speed transmission. The engineers that designed the truck put in a tow/haul mode as well as a sport mode. Both modes definitely make the truck feel different. Sport is for fun, tow/ haul is for work. The truck runs awesome, tows the trailer like they where made for each other. When the 5.0 is hitched it’s in tow/haul and forget it , drive it like the trailer is not even there. On the highway I regularly use the cruise control and the truck uses all 6 gears. Cruising on flat ground at 60 mph it would be in OD, yours isn’t?

[Cliff Hotchkiss]

Originally Posted by steve dunham

My truck came equipped with “ Tow / Haul “ mode . The way I see it , the vehicle manufacturer and their engineers put it in the vehicle for a reason .
When I tow or haul , I push the tow / haul button and go on my way
I don’t pretend that I am smarter or know more than the engineers or my vehicles computer .
As far as whether using tow / haul mode affects fuel mileage , I don’t know and I don’t care . If we decide to go on a trip and 2/10 mile per gallon is the deciding factor then I am selling the trailer .

😳 I could not agree more.....

[Defenestrator]

On older vehicles, there was sometimes a separate overdrive unit that tended to be pretty fragile, so towing in overdrive could be bad. That ended sometime in the 80s or maybe early 90s depending on the model.

What tow/haul does varies on the model, but if transmission temperatures are good and it's not "hunting" and you don't need engine braking, it's fine to leave it off.

I tow a 25' Bigfoot with a '16 Silverado 1500 6.2, and typically use T/H in the hills but not on flat ground. The manual says it helps trans temps, but they seem to be fine even climbing steep grades without so far. It definitely revs higher and engages lockup aggressively, as well as kicks in grade braking more. Makes for jerky shifts when not towing.

[Lanarkwanderer]

My Silverado 5.3 lt, gas, raises the alternator voltage about 0.5 V in "tow" mode.
I haven't noticed much change in fuel mileage.
The signal light "lane change" timing is doubled when in tow mode.
It also monitors if the trailer is plugged into the TV and gives a warning if the electrics cable has disconnected.
I generally keep an eye on the trans temperature indicated on the dash, but it's never gone up enough to be a concern, even with 6000 lb + trailers.
It may change the trailer stability programming, hill decent and builtin brake controller.

Bob

[ATHiker]

Tow / haul modes varies by manufacturer and may vary between models of the same manufacturer. My Tundra has a six speed transmission. Using tow/haul does not block out sixth gear.

[Carol and Mike]

I use tow/haul mode whenever towing. Don’t need to overthink it.

[Cliff Hotchkiss]

Originally Posted by Defenestrator

On older vehicles, there was sometimes a separate overdrive unit that tended to be pretty fragile, so towing in overdrive could be bad. That ended sometime in the 80s or maybe early 90s depending on the model.

What tow/haul does varies on the model, but if transmission temperatures are good and it's not "hunting" and you don't need engine braking, it's fine to leave it off.

I tow a 25' Bigfoot with a '16 Silverado 1500 6.2, and typically use T/H in the hills but not on flat ground. The manual says it helps trans temps, but they seem to be fine even climbing steep grades without so far. It definitely revs higher and engages lockup aggressively, as well as kicks in grade braking more. Makes for jerky shifts when not towing.

🤔What's the down side of just putting into Tow/haul when you are TOWING?

[Defenestrator]

Probably just slightly worse gas mileage and a bit more noise. Maybe less-smooth shifts if the tow rig is really overkill.

[Cliff Hotchkiss]

Originally Posted by Defenestrator

Probably just slightly worse gas mileage and a bit more noise. Maybe less-smooth shifts if the tow rig is really overkill.

Or maybe not, and the vehicle will probably last longer if used as it was designed. The forums are filled with horror stories about major issues
when people who "know better than the engineers "modified their rigs.😎

[Jon in AZ]

Originally Posted by Defenestrator

Probably just slightly worse gas mileage and a bit more noise. Maybe less-smooth shifts if the tow rig is really overkill.

That’s exactly what my owner’s manual says. Tow/haul on my vehicle is designed for towing at or above 75% of GCWR. No damage will result if used below that but you might experience more noise, rougher shifts, and reduced fuel mileage. (2014 Chevy Express 3500 6.0L, 6-speed automatic)

Different vehicles have different hardware, different software and different best practices. Read the manual.

[steve dunham]

I called the manufacturer of my vehicle and asked “When should I use tow haul
The answer i got was , if your owners manual says the trailer requires trailer brakes then at that point / weight use tow haul .
IE ; if brakes are required above 1000 lbs then use tow haul above 1000 lbs

[Bruce H]

Originally Posted by Bruce H

Ok, so does the "tow haul" cause the ecm to adjust the fuel mixture in the engine?

The reason I ask is that I had a 1995 Peterbilt tractor with a 425/470 horsepower Detroit Diesel engine and a standard, not automatic, 10 speed transmission. It was 425 hp when driven without the cruise control but flipping on the cruise control increased the horsepower to 470 by adjusting the ECM. That technology is now 25 years old. I admit that I have not kept up to date on the latest developments in computer controlled transmissions and engines but I find it difficult to believe that lighter weight vehicles designed to tow trailers would only use the computer to control the transmission.

[Lanarkwanderer]

Originally Posted by Bruce H

The reason I ask is that I had a 1995 Peterbilt tractor with a 425/470 horsepower Detroit Diesel engine and a standard, not automatic, 10 speed transmission. It was 425 hp when driven without the cruise control but flipping on the cruise control increased the horsepower to 470 by adjusting the ECM. That technology is now 25 years old. I admit that I have not kept up to date on the latest developments in computer controlled transmissions and engines but I find it difficult to believe that lighter weight vehicles designed to tow trailers would only use the computer to control the transmission.

Maybe it just changed the waste gate to provide more boost so less need to down shift the manual transmission ?

Bob

[Al and Cindy K]

Originally Posted by Cliff Hotchkiss

Or maybe not, and the vehicle will probably last longer if used as it was designed. The forums are filled with horror stories about major issues when people who "know better than the engineers "modified their rigs.��

What's the fun in that? When we bought our 16' Scamp back in 02, I had a 00 Jeep Wrangler and the wife drove a 98 Land Rover Discovery. It took one trip with the Disco to figure out the Jeep was a better option even though it was rated for a max towing capacity of only 1,500 lbs. I'd upgraded the TJ's suspension, brakes, tires, clutch and differentials and it was much more capable than what the engineers came up with.

Just messing with ya - I know where you're coming from but vehicles can be modified to perform beyond their stock capabilities and still be roadworthy. The Jeep is still around but that British built piece of junk is long gone.

[Cliff Hotchkiss]

Originally Posted by Carol and Mike

I use tow/haul mode whenever towing. Don’t need to overthink it.

Yeah think! 😂🤣😂

[nefldiver]

2500 gas or diesel tow. Haul is irrevelant

[LoneWolf04]

As far as GM tow haul features go it does several things and some were mentioned so far, and some haven’t.

Mentioned before has been the shift pattern. Holding gears longer is part of it.

Other items the mode does is increase line pressure in the transmission. This coupled with faster shift commands reduces slippage on the clutch packs. In return, it keeps your clutches from wearing as much and since the clutches aren’t slipping as much during engagement, it keeps your temp slightly cooler as well.

One thing I have noticed when towing with a 2500hd. If the trailer is too light and you use tow haul, first couple shifts in town from a stop light can be slightly rough engagement due to the extra line pressure and faster shift command.