I have a Prodigy 90185 brake controller that was installed in 2008. It has always worked well, and I have always left it connected and in place in my tv. I have also had the car battery replaced once since then. I had my timing belt replaced and to get to it, the battery was removed. After picking up the car at closing time, and on the way home I noticed a red light shining on my pant leg near the controller. Much to my dismay, I saw numbers displayed that varied with the car breaking. (No, I was not towing the "Suite Escape".) After arriving home, I still had a numerical display that did not shut off, even with the key out. Of course I was worried that there would be damage either to the unit or a continuing draw on the battery. I tried and failed in my effort to disconnect it. I called Prodigy only to learn that they were closed. (They are on the east coast and I in the west.)
However, they were to re-open very early, my time. I then checked the wiring diagram and noticed that I had both a white wire and a black wire to be connected with the white going to the negative and the black going to the positive poles of the car battery. Both colors were hooked to the positive pole on my battery. I was fearful the dealership where I had the work done made an error.
The next morning I called Prodigy tech support and they explained: When the battery was re-connected it probably sparked sending multiple impulses to the unit and "confused" it. I was to un-plug it, wait at least 3 minutes, and plug it back in. That should do the trick.
IT DID! I also learned that since the black and white wire were together in the green sheathing (wire covering), that the white wire was ultimately going (when the trailer was hooked up) to the trailer battery. Additionally, it is ok to keep the unit plugged in; it has an automatic shut-off (when working properly).
What a relief to learn this. Hopefully this will help someone else.
Tech support was great.