Tow/Haul button: what is it for?

Per the owners manual...

DrewE wrote:
(I say "I would" because my motorhome is old enough to lack the tow/haul mode.)

And it works just fine without it.....right ??

My 28" has a 450 so the situation is slightly different BUT......I have yet to feel a real "need" to use tow/haul except descending long grades. Even when also pulling a small trailer.

The transmission downshifts when it needs to and it goes along just fine.

So my advice is: Try it without using tow/haul. If the engine seems strained and/or it downshifts often then try it.

If you are whizzing down the road and you think everything is fine.....then it probably IS.

As others said, it alters the programming of the transmission controls to work better with heavy loads. Since a motorhome is always a heavy load, I would leave it engaged all the time. (I say "I would" because my motorhome is old enough to lack the tow/haul mode.)

Besides the shift points themselves, it tends to make the torque converter lock up more readily (I think) and may alter some of the details of the timing of the actual shifts in an effort to keep the transmission operating temperatures down.

For the record I too own a 2012 24' E-350 Class C that I have logged 35,000+ trouble free miles in over the last 3.5 years...

Anytime you are running anywhere near your GVWR or towing anything, you should have the Tow Haul engaged. Anytime you are descending a long grade you should have the Tow Haul engaged. About the only time you don't need it is when lightly loaded and descending a very slight, 1 or 2 per cent grade or running on dead level terrain and no head wind.

Tow Haul re programs the engines ECM {Electronic control module = co outer}, resetting the shift points, locking up the torque converter which eliminates friction which = needless heat making your transmission run significantly cooler and your rig run much more efficiently.

As you descend long steep grades in TH the engines compression acts to brake the coach and all but eliminating the need for braking and you will not burn a drop of fuel all the way to the bottom of the grade.

TH is probable the least understood and utilized function of any vehicle. Read your owners manual and know that the salesman you dealt with is an idiot.

:C

Tow/haul cause the transmission to shift at a higher engine RPM for each gear. When the vehicle is under a load (like towing), at slower speeds, the transmission will shift up and down way too much. Sometimes, the transmission will not down-shift at the right time to keep the torque up too if you do not have tow/haul engaged. When needing to speed up, and you're expecting a down-shift to occur, sometimes they just don't.

With Tow/Haul, the shift pattern is a bit different. The transmission will stay in lower gears longer, and when climbing hills, or towing a load, the transmission will (kind of .. sort of ...) lock into a lower gear to keep the torque up. Somehow, it knows how to do this.

So, if you are on hills or in town with lots of stop and go, tow/haul is great! If driving interstate, flat and steady, and shifting is minimal, then you don't need tow/haul activated.

Another advantage of tow/haul, that I find more beneficial that then different shift pattern, is the fact, when activated, and coming down mountain roads (interstates), tow/haul will keep your transmission in a lower gear without you having to manually down shift. The engine will rev, but it will keep you in a lower gear, thus prevent you from having to ride your brakes, or manually down shift.

Once you get to the bottom of the hill, press the gas peddle slightly, and it will then shift back up to the next gear. It's really sweet the way it works. I really couldn't tell the big difference until we hit the mountains of Virginia, West Virginia, Kentucky, Tenessee, and South Carolina that first time. And then .. Oh Wow!

Now, whenever I tow the trailer, I just automatically push the tow/haul button "on". Even on flat ground, in town, the higher shift pattern makes driving much nicer too.