[mentalreboot]

I see on my 11 I have three modes of operation
D-auto
manual by limiting the top gear used
tow haul plus the above.

Is putting the trans in manual shift mode WITHOUT tow haul activated and setting '5' ANY different then using the trans in auto on D?

Can tow haul be used for a snappier response 'empty' with the assumption mpg will be less or is that a no-no if not loaded or hauling?

Thanks and Happy New Year.

2500mi on my '11 now.

 

[Murph0408]

i'm curious to hear about the difference between doing tow/haul and doing the shifted option in D. from what i can tell they both serve the same purpose by knocking out the higher gears depending on what you shift it to (1-5). i might be wrong though so we'll see

 

[TNC]

It would be nice if the TransEngineer fellow would respond on this, and perhaps he will. But just for discussion fun, I'll throw in 2 cents. The only thing I seem to notice in the cab from a display and seat-of-the-pants feel in the truck's operation, is that MDS is disabled when the trans is in its top gear and not drive. The tow/haul mode seems to do the same thing. In tow/haul mode, however, I expect some other factors are in play that may range from fluid pressure, how long the trans holds in given gear at certain rpms, and similar issues that would help towing and keep down heat in the trans while towing. I tend to think the manual shifting of putting the trans in its top gear rather than in drive mainly just disables MDS. I see no rpm difference or notice any shift point change when in drive or in manually selected top gear. If there is it must be very subtle. Now, when towing a trailer with the tow/haul mode engaged, I see a noticeable ability to stay in a given gear longer, but I didn't try towing with the truck and the tow/haul not engaged. I wish I had just to test that possibility. The trans may seem to act the same in either case when you actually have a tow load, because you're mashing the gas pedal harder and the computer reads that in either case. Still, I bet there are other beneficial factors at work in tow/haul mode to protect the transmission and increase performance somewhat.

 

[snrusnak]

^ditto to what TNC said.

Putting it in "5" on the EVIC disables MDS (for hemis....4.7L's don't have MDS). T/H holds gears longer, possibly increases line pressure (not sure), and locks out the second overdrive and rearranges the shift pattern to include 2nd prime. I'm not sure if manually shifting (without using T/H) rearranges the shift pattern to include 2nd prime, but I think it does.