2012 RAM 1500 W/ TOW HAUL?

Something else to experiment with...

Descending a grade, With my 2013 6speed, I've found with TH on, the computer downshifts a gear or more depending on how hard I apply the brakes. With TH off, the computer coasts in overdrive as long as it can.

With cruise control on and TH on, it downshifts multiple gears to maintain speed going downhill. The only time I manually downshifted going down hill is if I wanted to slow down below what I had cruise set at (curvy downhill grade for example.)

We have a 2010 Hemi 5.7 2500, and tow a heavy travel trailer.
The tow/haul does seem to be easier on the engine in the mountains. When going down a hill, I step down the trans manually to hold the rig back. At times, the rig works better in normal mode at freeway speeds (60-62 mph). Just play around with the trans--sometimes tow/haul works, sometimes not.
As far as the "hunting" issue, we had a dealer in Rapid City do a reprogram and the truck runs great now.

In other words---- you can't use it to downshift. You can only use it to keep the tranny from UP shifting.

To clarify, you can use it to downshift, but the shift will only happen if you are below the max rpm and speed parameters set for the gear selected. If you are cruising at 75mph in 6th and try to select 3rd the computer won't allow the downshift as the rpm would redline, but if you were coasting down a hill below 60mph and shifted to 3rd for engine braking it would.

Engine braking is one of the more common uses for manual shifting when towing. Tow/haul mode will downshift automatically under the right conditions but sometimes it is not enough.

Modern trans do not hunt per se. Given a particular load it will select the appropriate gear. And stay there.

That does not mean undesirable shifts never happen. The trans does not know if you are 50 meters from cresting the hill or not. And loads are constantly shifting with grade and wind. Mostly only matters when cruise control and towing are combined.

joelyn wrote:

camp-n-family wrote:
The electronic selector on the gear shift will regulate the top gear you choose. For example, if you select it to 3, the transmission will shift regularly to 3rd gear and then stay there. It will no longer shift beyond that gear.

You would use this feature when towing if the tranny is hunting gears, say in the mountains, and you want it to hold a certain gear for better power.

THATS THE BEST DESCRIPTION THAT I HAVE HEARD YET.
ty

Great explaination. May I add to it:

You must select that gear prior to "reaching" it. If you are already in 6th, then try to select 5th, it will not GO there until you slow down enough for the computer to tell the truck to downshift into 5th (then it will hold it there).

In other words---- you can't use it to downshift. You can only use it to keep the tranny from UP shifting.

TO THE OP:

If your 22' is anywhere as light as my 19' is...You will not notice much difference using the tow/haul at highway speeds. You will see a small difference getting up to speed. Not much, that HEMI isn't going to be pulling hard with a light-weight trailer.

However, the additional braking provided by the earlier downshifting is appreciated.

My belief is that the software algorithm leading/trailing hysteresis over lap is
NOT well done

So the computer is caught in no man's land...dropping down into a lower gear and
then find that the sensory input move is into the leading hysteresis for an up
shift. Throttle position input also factors, as does the other inputs to the
computer (temp, rate of change in all of these inputs, ambient vs whatever internals, etc)

Tow/Haul (IMHO) was invented to save the automatic and engine...where folks who
have manuals either know the HOW2 or decide to shift themselves from their input
(tach, sound, etc)

Being in the wrong or not the best gear for that moment won't kill the engine
or tranny instantly...but will wear/tear either/both over time...

Lots of folks mention "hunting"... What driving conditions are you placing on the vehicle to cause this?

As an engineer it sounds to me like a software malfunction in the transmission computer. If it fails to find the best gear for optimal output, why doesn't it give up, select the nexr lower gear and wait for conditions to change? Is it a fast oscillation between gears, or slow over minutes or hours?

Has anyone had a dealer run a computer diagnostic after the hunting occurs?

I guess I've never experienced it myself, hence all the questions. Sometimes I forget to turn on TH, still haven't been on a hunt.

Typically I'll use tow haul when I need to get up to speed or on any terrain that isn't relatively flat. On flat land I'll disable it once up to speed. Sometimes the engine load is so low that MDS will turn on. I keep an eye on the current engine load and trans temperature. If I ever find that the load is too high or the transmission starts to hunt then I switch it back on.

joelyn wrote:
NOT SURE IF THIS IS WHERE TO ASK, if wrong mod can u move it.

have a 2012 ram 5.7 w/ tow haul mode. is this used only when climbing a mt. or steep grade while towing a 22ft travel trailer? or are there other times it can be used?
thanks

Towing and oh yea, hauling.
See O&M manual.

Useful tip, say a jackhole makes a quick stop ahead of you. Take your foot off the gas and Shift left (counter clockwise?) to the minus and hold for a few seconds. The computer will do a controlled fast downshift to 1st gear and really add a lot of braking power.