Chrysler Repair: transmission jammed, manual roland, dodge caravan

Question
QUESTION: 1996 dodge caravan with 220K miles .  I bought used at 186K miles About a year ago my van would stay insecond gear when I started out and later in the day would go into third,  I added fluid and it worked okay for awhile but now it is doing it again.  At the moment it will not shift at all and is stuck in the driveway in reverse so I can't even start it to move into garage.   
Cant't move lever into any other gear. I read something about a speed sensor output device. Is this it. Could it just need a new filter since I neve changed it.

ANSWER: Hi Paul,
The gears are shifted by a vertical shift rod on the side of the trans that faces the front of the van. You could try rotating that rod by hand to see if you can free up the action.
The refusal to shift is a symptom of the transmission sensing it has some sort of a problem that poses a risk of unnecessary damage and so it disconnects the relay that powers the shifting. You would do best to get it to a nationwide autoparts store for a free fault code readout of the transmission controller memory for determination of any codes. Then you will have an idea of what is the cause. An independent transmission shop will do the readout for about $40. Ask for the code numbers, what they mean, and what they recommend doing. Then let me know and we can compare to the shop manual.
Roland

---------- FOLLOW-UP ----------

QUESTION: I will follow your advice and try to get a code readout, but from your
experience what are some causes/solutions to this problem?
I saw on youtube a couple of guys replacing the input speed control sensor
to solve this problem.  Is this a likely solution?  Also will replacing the filter have any effect on this problem?

Thank you for getting back to me so soon
Regards,
Paul

Answer
Hi Paul,
There are 28 possible reasons for being in Limp-in mode so don't assume anything about what to do without a code readout. Otherwise throwing parts at the transmission can be very costly and frustrating. I donbt the filter would be the answer either unless the internal pressures are low and then too if the filter is clogged it bodes ill for the mechanical parts that may have fragmented off pieces. So don't do anything until you get a code readout that tells you what the transmission controller sees as being wrong.

Roland