Transmission problem or just electrical

I have a Dodge G caravan 1996, 150,000 M Transmission rebuilded 3 nonths ago, the problem came on only two weeks ago.
It is allways the same thing . Driving over 45 miles My wipers go on
for one or two times just before the tranny suddenly downshift to 2nd gear and refuse to go any higher. I have to pull over, put it in park, kill the engine, and then re-start it, it works fine for another two o three days. I did a computer scan and I got a faulty transmission relay code, I don't even know where that relay is or if can be a problem in the circuit some where before or after the relay, maybe the BCM .... ? on the other hand the engine light is giving mi a code 12 (Battery disconected recently) but the battery haven't been disconected in a year. At least with the wiper thing I get a warning before happens, so I can slow down, at 80 miles the engine gets in the 7,500 rpm when that happens, can't be good.
I'll appreciate any idea, I'm lost. Thanks

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file
Upload is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.