It turns your 5sp auto into a 3sp auto. As I understand it, it locks out the other second gear and disables overdrive. That's what the "OD off" button mine does. I think in 04 or 05 they changed it to a "tow/haul" button.

 

I have a question to elaborate on the OP's question.....

As anyone with the 4.7 knows, these trannies in these things are so freakin annoying. It'll shift into 5th as Im climbing a hill, then have to downshift, usually waiting until it needs to go into 3rd, making it sound like Im trying to fly up the road. To aleviate (sp) this, I hit the tow/haul once, putting it in that mode. (twice is OD) Ill ride around town in this mode, until I get to the long stretches of 45mph, where the rpms would be 2kish or more. Then I put it back into "regular mode", for lack of better term.

I know keeping it in tow/haul wont hurt anything, but could switing back and forth eventually be detrimental to the tranny? Ive been having some hard downshifts lately coming up to stoplights (I believe its the 2-1 shift), hope that particular problem isn't correlated to my driving habits....

Lonestar..... Are you referring to "OD" when talking about turning it into a 3spd, essentially? 'Cause when I have it in tow/haul, it stays in 3rd until I hit about 52mph, then it'll shift up one more. I only found this out when I had to drive an hr with a large load of wood on the back.

 

Well actually my truck is an 07 and it has tow/haul mode and o/d off. Push once for the tow/haul mode and twice for the o/d off.

 

tow haul and O/D off are two different things (hence why some have both). O/D off doesnt do anything to the gearing, just prevents the tranny from going into O/D. Tow haul doesnt disable O/D, but changes the gear ratios in the tranny to allow for towing.

Switching either mode in and out shouldnt hurt anything, but theres really no point. In the case of going up/down hills, just keep it in the mode. even 3k rpms is nothin for this motor

 

That's why I added the caveat. 03's don't have a tow/haul mode, just OD off/on. Wow, first year (hemi/545RFE) gets screwed on everything (except we can do the TMR mod...)

 

I have heard guys say the you should drive around with the tow/haul off. They claimed it was better for the transmission. That it reduced trans temperature ans was beneficial to making your tranny live longer.

 

I'd imagine theres some logic to that theory Bama... It allows the truck to not downshift/upshift/downshift/upshift like crazy, like these 4.7's do anyways. I'm not sure how the hemi Rams act, but my 'Rango doesn't really have a problem with this, I'm guessing 'cause it has enough hp/tq to climb the hills in that high gear, no need for downshifting. My Ram on the other hand, the tranny is the single most annoying thing I can find about it (besides the flickering HID's, but thats not really the Rams fault ) Leaving my house, my street is about 1/2 mile or so, straight uphill, till I get to the main road. If I try to keep it @ 25-30mph, like I do, and keep the mode in "normal", the damn trans will shift.......4-5 times I'd say.

 

It feels like it shifts harder with tow/haul on.

 

It feels like it shifts harder with the tow/haul on.