Dodge Repair: 02 dodge cummins wont shift properly

Question
my 02 dodge 3500 dodge cuinkingmmins wont shift properly, 2 days ago it wouldnt shift to 3rd or fourth, it would shift to 2nd idle all the way up to 3k without anything if u let off of the throttle a bit it may up shift but not always, i thought at first it was transmission filter. so, i changed the filter and checked the fluids, the fluids were burnt and completely black. so, i changed it; turned the truck on and it shifts to 2nd fine, but wont shift to 3rd at all, it completely loses power at 20-30mph now. i heard that u were supposed to tighten the adjustable bands in the tranny. but i also heard that it could be the governor pressure sensor or another sensor. if you have any information i'm all ears. also, i was wondering if it could be the tps sensor and another thing, the torque converter may be completely full of that black burnt tranny fluid that may need to be drained and refilled. thanks for ur time

Answer
Hi Ronjon,
I don't have the '02 truck manual (but I checked at Allpar.com and find there are more that a half-dozen transmission used in the Ram of that year, and possibly 3 or so in the Diesel) so I can't be certain which transmission you have there. But if it is an electronically controlled unit (as opposed to the older automatic designs which are hydraulically controlled) then those units (as used in the cars/minivans) do have a design that when there is sensed by the electronic transmission control module that a problem has occurred with the transmission it will disconnect the automatic transmission electrical control relay and will then only operate in second gear until the problem is solved. It is called being in "limp-in mode". So given the history of the transmission fluid being burned I suspect that you may have an electronic transmission and that it is indeed in limp-in.
These transmissions also have a built-in diagnostic system which records various possible malfunctions as 4-digit code numbers that you obtain by means of a fault code reader that plugs into a socket under the dash near the steering column.
So investigate whether you have that type of transmission and if so go to a shop and ask them to do a code readout of the transmission control module. Let me know the number(s) if present and we can go from there. Based on the number and what needs to be done to correct you will then know whether there is internal damage requiring opening it up or not, and if not, then certainly as part of the remedy you will want to completely replace the transmission fluid via a pressure drain out which gets rid of not only what is in the torque converter but also in the transmission cooler and the connecting hoses so you will have totally new fluid in it.
But before doing that let us see if there is a fault code or not.
I do have the '04 manual which may apply. The model of the transmission may be indicated by the VIN or by a label on the transmission itself so ask at the shop for which type number of transmission it is.
Please read the PS (below) and respond to it.
Thanks for doing that.
Roland