1st gen transmission stuck in high gear

My 2000 v8 tundra has a P0753 shift solenoid A Electrical code. The truck is in a high gear, it will still shift manually through the gears. I have topped up the fluid, rest the code, it fixed it’s self briefly but now it’s back for good. Does anybody have any info about the process of swapping out those solenoids? I can’t seem to find too much online, any info on which is which solenoid? I’m a millwright by trade and worked on my vehicles a bunch just haven’t really been into a tranny before

 

I would probably refer to the Field Service Manual (FSM) that can you get online by subscribing for a day, week or month to Toyota TIS. You can generally print them out as well or save the pages to your computer. It's take a 1/2 day to do it though.

 

Did you only top up trans fluid? If its old, I'd suggest a drain/fill or two, flushing is even better and has solved many folks solenoid shift issues for good.

 

I had pretty much the same issue on my 96 Camry. Was prepared to put a whole new trans in it but I ended up flushing out every drop of the old fluid (not usually a good idea but nothing to loose) and changed the filter and it finally started shifting again. I had to drive it quite a bit after changing the fluid before it started shifting right but it finally did. It was throwing solenoid codes and everything. I found pinouts for the solenoids out of the TCM and verified that it was indeed telling the solenoids to fire they must have just been gummed up. I also triggered the solenoids with a power probe with the car off and the trans pan off and could hear the solenoids firing. Part of the valve body would have had to come off to get to the solenoids that were throwing codes so I figured fluid change was the simplest thing to try.
My fluid was really seemed really thin and was pitch black.
Still have that car as my winter beater and after 10k miles or so it's still shifting fine.
Not a tundra but figure the transmission in a Camry and a tundra have to be at least somewhat similar.

 

https://youtu.be/PWckXDrND1M

right around the 7 minute mark. Doesnt look too hard to get to.