Chrysler Repair: 1990 new yorker transmission problem, inner fender, chrysler drb

Question
Our 1990 New Yorker had the transmission rebuilt about 20,000 miles ago, it has never felt real solid when I put it in reverse,and it has gotten worse, last week when I started out, the car felt like it is missing.  I checked the trans fluid,and it is brown and smells burned. I took it back to the shop that rebuilt it, and he says he can't get any ccommunication when he puts it on the computer read out, that the transmission control computer is not locking in, and the clutches are burning, that we need a new transmission computer.  Once the car warms up, the shifting is fine. Does this sound right, also where is this transmission computer located on the car?  Would it be OK to replace it with a used one?

Answer
Hi Rich,
The transmission computer is on the right side inner fender wall, at the front near the radiator. A used computer would be OK if it was set up for the same car and year. Before going that route, be sure that the code reader is being connected to the blue data link connector that is under the dash on the left side, and not to the black connector in the engine compartment. They are different shaped connectors, and the blue one is for the trans readout only, the black for the engine only. I am not sure what is meant by "not locking in". The burned fluid suggests that you would want to do a power flush and be sure to use ATF +4 fluid in the refill. I hope you can get to the bottom of this without too great an expense. If you get some codes using a Chrysler DRB II or equivalent reader let me know what they are.
Roland