when to use "econo mode" on Allison 5 speed tranny?

From my research, it changes the transmission behavior. The modes have to be programmed. On mine it supposedly modifies the shift points to give better fuel economy. I tried it for several thousand miles and found no noticeable change in fuel economy or shifting behavior. It could be that mine was never actually programmed. I just leave mine in normal mode.

My recollection - economy mode places your vehicle in mode where engine/air conditioner work at reduced performance and greater fuel efficiency. Many use that mode when they do std driving and switch out when then have to pass/need acceleration.

It is supposed to hold the gear longer to prevent constant hunting between 5th and 6th gear when highway driving on rolling hills and flat roads. Doesn't do anything for city or mountain driving. More or less holds the gear a little longer so it doesn't shift as often between the higher gears.
I don't use it because it seems not to make a difference on my coach and it doesn't change my mileage

Pretty much.....never. The difference is negligible and not worth the effort of even thinking about it.

As stated above, I have never used it, having the same tranny I want every bit of performance rather than saving a mile or two per gallon of fuel. We do the majority of our RVing in the mountain west region of the country where traversing extreme elevation changes is the norm, our toad is pretty heavy by normal standards and we need every bit of torque, which is reduced in eco-mode.

Plus fuel is much cheaper than RVing in past years, can't say we even give much thought to mpg, eco mode just doesn't make sense for us. In fact, there is no difference when towing our heavy toyhauler around this great country. Hard to fret about mpg when RVing, reduce mpg is par for course and is just part of the the lifestyle that is commonplace for this fabulous and enjoyable past time.

Allison says among other things that ONLY at higher throttle positions is there any difference, so on flat ground you will NOT notice any difference.

btilfan wrote:
Is it for city or country driving? nothing listed in the manual.

This pdf will identify and explain every function of the Allison World Transmission: http://www.rvtechstop.com/resources/allsonok.pdf

Made the Link clickable

Interesting read. I have a different alt-mode in my Motor home (Grade brake) but the manual confirmed what I understood

Grade brake is used in hilly country and can be used all the time.

Economy mode in flat land and ideally when NOT towing.

How to decide:

if the tranny is "Hunting" (Switching in and out of top (usually) Gear) Turn it off.

I would think this would be of more use in areas where your speed is changing.. Like in the city with stop and go driving than on the freeway where it more or less goes into top gear and stays there.

On hills you need to listen to your engine. if it's struggling turn it OFF.

(I know not everybody listens to the engine. I had some issues (Rodents in the ignition primary it turned out) and my wife could NOT hear the misfire which was clear as a bell to me).

There is more to it than what is in that pdf. From Brett Wolf, head of the FMCA technical commitee
The Allison transmission WILL NOT allow you to lug the engine, it will downshift at the bottom of maximum torque regardless of your actions.This up-shift on downgrades can be disconcerting when you allow your speed to climb too high, for then the up-shift happens at approx. 2,600 RPM(diesel), leaving only your service brakes to slow your speed.

I have studied the Allison transmission TCM and its interaction with a diesel engine TCM for some time.I'm still an amateur though.

2000 Winnebago Ultimate Freedom USQ40JD, ISC 8.3 Cummins 350, Spartan MM Chassis. USA IN 1SG retired;Good Sam Life member,FMCA ." And so, my fellow Americans: ask not what your country can do for you--ask what you can do for your country. John F. Kennedy 20 Jan 1961

On my Tradewinds, running in economy mode causes the transmission to NOT downshift out of 6th gear on gradual grades as early or often as it does when NOT running in economy mode. That occurs when running with cruise control on which I use as often as I can. I think that early shift down to 5th which requires the RPM to go up could have something to do with mileage but cannot substantiate that because I almost always run with economy mode engaged.

When I am in the mountains, I obviously do not run with cruise control or put the transmission in economy mode.

All that to say these are only my observations which don't prove anything. It's just what I do.

Happy travels. Arnold