My 2012 caravan has 184,000. One day, out of the blue, while driving down the road the van downshifted while doing 55mph, and would shift past 3rd gear after that.

I took it to to a local dealer who drove it, and coded it, and told me it said something about “4th gear pressure” and that my transmission is basically shot. Being as miled up as it is, and the issues I read concerning their transmissions, this seemed plausible.

Dropped $1500 on a transmission with only 18,000, had it installed by my mechanic, not the guy who coded it, and it ran great for two days. After two days it started doing the same thing.

My mechanic has since tried numerous things. Said the codes that come up are random. Different almost every time.
Does anyone have any kind of ideas as to what else to check? Clearly it sounds as though it was never the transmission but potentially a wire that has failed, or something with the computer, or ECM?

At a loss here and any any help would be appreciated. Thank you.