05' Tow Haul Switch

[ronsr]

I recently ordered an 05' 2500 CTD with automatic transmission. I am curious about how the tow haul switch affects transmissiom operation.

 

[KCJackson]

On the 48RE, all the TH button does is turn off OD. On the 545RFE used with the Hemi and hopefully the new 5 or 6 speed automatic for the Cummins, the TH button actually changes the shift points (quicker kickdown, longer holds to upshift).

 

[BHolm]

The owners manual describes it a little differently I think. I don't have it in front of me so this could be all wrong but... I swaer it said that using the T/H button will give you a grde braking 4-3 downshift under steady braking. That leads me to think that it doesn't just lock out the OD. In fact, I can't imagine trying to tow on the highway in third? How many rpms is 70 mph in third? I guess locking out the OD just doesn't make sense to me? Am I missing something?

 

[tschwab]

The owners manual describes it a little differently I think. I don't have it in front of me so this could be all wrong but... I swaer it said that using the T/H button will give you a grde braking 4-3 downshift under steady braking. That leads me to think that it doesn't just lock out the OD. In fact, I can't imagine trying to tow on the highway in third? How many rpms is 70 mph in third? I guess locking out the OD just doesn't make sense to me? Am I missing something?

BHolm - I'm with you on this - The manual DOES in fact say it gives you grade braking, I also believe it says that it changes shift points as well.

 

[GaryCarter]

For the 2005 model, it does change shift points, adds grade braking, but it does NOT disengage OD.

There is at present no way to disengage the OD on the 2005 48RE.



Mike

 

[KCJackson]

I'll be happy to be wrong this time That would leave the question, if the 48RE was capable of handling grade braking and shift adjustments all along, why wasn't it available out of the box in MY2003 when the 48RE was first offered?

 

[tschwab]

For the 2005 model, it does change shift points, adds grade braking, but it does NOT disengage OD.

There is at present no way to disengage the OD on the 2005 48RE.



Mike

Gary,

That is good info to know, where did you get it? Does this make the '05 48RE better than previous versions for towing? What do you see as the advantages of this?



Thanks - Terry

 

[BHolm]

And I'd be happy to be right on this one :-laf



Since my truck only has 500 miles on it, I haven't had a chance to try it out. If it works anything like the same feature on my old Allison, it is a VERY nice feature for those like me who tow in the mountains. For me, on the Chevy, it used to mean that coming down Monarch Pass (steep and long) that with up 8000lbs behind, brakes are almost unneeded.

 

[GaryCarter]

Terry, I got my info at the wheel (see sig).

I'm not qualified to compare to the previous 48RE; the last Dodge I drove had the 47RE (2000 model).



I would rather still have the option for OD lockout. IMO there's no substitute for being able to pick your gear to suit conditions. Last truck was a Ford which also had no option to lock out OD- it was an irritant and fuel sucker in rolling terrain.

Mike

 

[tschwab]

Mike,



I tend to agree, I was always told to "lock out" OD when towing grades, etc. It prevents the transmission from going back and forth between 3rd & 4th which causes alot of heat, which in turn will kill the transmission. Hopefully DC in all their wisdom has done this for a good reason, if not... well, then they get to fix it under the 7 year/100K warranty if it goes bad.



Fortunately, previous 48RE's have had a pretty good track record.



Also - Didn't understand what you meant by "at the wheel" (see sig). Did not see anything there??

 

[BHolm]

My '03s run rolling terrain daily with loads. The 48re seems very good at just staying in OD. It is MUCH better than the Ford or Chevy at this. Those V8 diesels, albiet with 5 sp autos, jump out of OD like it isn't even there. Haven't had a need for an OD lockout on a 48re yet. I have pulled a 20k lb trailer through the mtns with the dually too. Even with that load it jumps into OD and stays there pretty well. Two work trucks with 48re's, and extremely pleased with them so far!

 

[GaryCarter]

Didn't understand what you meant by "at the wheel" (see sig). Did not see anything there??

My apologies; I didn't intend to be obtuse. Either I did something wrong on the last post or the forum software is set to show the signature at the first response only. You'll see my sig at my first response way up near the top.



That's the long way of saying a 2005 with the 48RE is what I'm driving now, so that's how I know. I have yet to make it to the mountains to see how she does on some real grades with the trailer.



With respect to the lack of an OD lockout, I think there's still a place for that. When you're towing at 55 in the hills, OD is really too tall a gear with the 3. 73. My preference would be that they give us the tow/haul button to change the automatic shifting profile, AND give us a position on the gear selector for EVERY speed (1-2-3-OD).



Mike



PS- while I'm dreaming- give us a manual override on the torque converter lockup too, so we can lock her up in any gear for climbing and descending. :-laf