Transmission help

Ok guys I need input/help. I will break this down by events. 2005 Tacoma 234k automatic v6

Ok took the truck in for hard/violent down shift, first shop had scanned it and pulled the pan, no codes and no metal in the pan and fluid looked good. they said they didn’t know what to do next,
So took it to another shop
They had it from the day after thanksgiving up till about a month ago. they supposedly put a shift solenoid in it, that didn't ohm out. Had the same hard down shift. Said it had to be a stuck valve. Truck sat there for 2 month with no further work or estimates etc.
I picked it from there and Took it to the latest shop.
Did a transmission relearn and another battery something or another told me the drove it for like 30 mins and never did it, then took it back out and it started to do it again. They said it was also something wrong with the valve body, and just replacing the valve body is risky. so I ordered a Toyota rebuild, they put it in and said it’s still doing the exact same thing a hard down shift thru the gears. But Toyota doesn’t pay labor to pull it back out, they priced me a justins not jasper transmission at the same time as the Toyota rebuild but it was 1800 more roughly.
I have a hard time thinking a fresh rebuild does the same thing as my original transmission. My thinking is it an electrical problem or a sensor or something like that. Any thoughts or suggestions would be appreciated.

 

I am no transmission guru, but I think it is important to know if the hard shifting is between certain gears or present in any gear. @gearcruncher is a transmission mechanic and may offer some guidance.

 

Also, was the torque converter replaced?

 

The hard down shift was between 2-1 originally and then went from 3/2 as well. I do not think the torque converter was replaced

 

https://www.tacomaworld.com/threads...th-pics-for-second-gen-4-liter-trucks.289913/

There are some technical service bulletins for bad wiring on the 2005 Tacoma that cause harsh downshifting
Checking TSB,s would be a good place to start .

I also beleive you have a wiring issue but before I send you on a wild goose chase , I highly suggest some pressure testing to begin .
A pressure test is going to tell us if the transmission is good or faulty .
If you have codes stored in memory , its going to shift hard
https://www.transmissiondigest.com/diagnosing-a750e-f-2-3-flare-after-overhaul/


Needle in a haystack that nobody has the time to diagnose .
Torque converters always come with a fresh rebuild

 

I had this same issue when I bought my 2005. Turned out to be a corroded connection that tied into the internal wiring harness inside the transmission. Replaced the internal wiring harness and truck shifts like normal now.

 

Did you do that replacement yourself or take it to a dealership or other shop and have it done? Just wondering how easy it is. My son's '05 is having some intermittent hard shifting and I want to rule out the simple stuff first.

 

I used to own a Honda Fit that started shifting wonky and throwing codes, had about 130,000 miles on it at the time. Based on the codes I was told I needed to get the transmission rebuilt at about $2000. I dropped the car off and got a call 30 minutes later and was told to come and get it.

Before dropping the transmission, they found a wire that mice had chewed the insulation off. It was shorting against metal causing the problems. They shrink wrapped the wire and charged me $50 for 1/2 hour labor. The car lasted another 100,000 miles before being totaled when a distracted driver rear ended it at a stop light.

 

I did it myself