Engine code P0748 comes up on the scanner

Is solenoid on the outside of the transmission or does it require to be opened up. This is a 1999 durango 4 wheel drive with a 5.2L V8. The vehicle goes but it is really slow taking off. It was a pint low on transmission fluid. I had been driving it through out the day about 105 degrees outside on stop and go errands. I was at a red light and when I went to accelerate the vehicle was really sluggish and hesitant to go. After reving the engine it took off across the intersection where I pulled into a service station and checked the fluid.

I added the pint of transfluid which didn't do anything to solve the problem. I only lived about 1 mile away so I limped it home and waited a day and then hooked up my OBD-ll and got the code P0748. Is this something simple that can be done without taking to a trans shop. Can you tell me where this governor is located or what it looks like, how many wires might be on it. Any information is better than what I have. Thanks appreciate the help. Mitch