Shift solenoid valve SLU

Sup guys, feeling a bit frustrated so hoping maybe someone might be able to help. First off I'm a big rookie when it comes to cars so be light on me. I got a check engine code reading P2759. Did some research and got a couple things on the check off list for possible issues. Got my tranny filter changed about a year ago. I read check for possible leaks or low fluid. Drained and got quite a bit. So fluid wasn't the issue. Drained and opened the pan and checked 4 of the solenoids that had the two prongs on car battery. All seemed to be working. Wasn't sure how to check the other solenoids to see if it was working properly as they were the smaller ones with only one prong.. Checked for loose wires harnesses etc. Not knowing what might be the issue I put the pan back on and filled the tranny. Check engine popped up again after a mile and now truck revs at 35-40 mph. Didnt have any issues before. Drove fine, no issue with shifting or slipping. At this point I'll need to pinpoint the problem and see what will need to be replaced. I'm most frustrated as to find out which of the solenoids needs to be replaced and which is which. Hoping this isn't a bigger problem than it should be. Any suggestions or opinions appreciated. Thanks in advance. - James

 

Which engine do you have? The 4 cyl and V6 use different transmissions.

 

You say “No issues before”?
Is there a possibility you pinched the harness when putting the pan back on?

 

Just because you got a good bit of fluid out when you drained it doesn't mean it wasn't too low. If you have the 4.0 liter engine the transmission need to go through some heating ritual before you can check it properly.

 

This is for the 4 speed automatic
https://www.tacomaworld.com/threads...sions-write-up-your-4-speed-automatic.325531/

This is for the 5 speed automatic . Considering you are talking about an SLU solenoid , I believe you have a 5 speed
You had the engine running when you removed the overflow plug on the pan ?
https://www.tacomaworld.com/threads...th-pics-for-second-gen-4-liter-trucks.289913/

 

It's a 6 cylinder.

The truck was driven for a few miles. When I finally drained the fluid the pan was hot to the touch. I'd say around 4 1/2 quarts.

 

So , there can be many issues causing your codes .
At present , I think you are very low on transmission fluid or one of your solenoids is not communicating through the wiring going back up to your computer behind the dash .
That overflow plug on the bottom of the pan needs transmission fluid to trickle out when the engine is running .
If the check engine light is popping up shortly after the truck runs , the computer in your truck has placed your transmission into limp mode .
Double check the trans fluid , then record the codes on paper and clear the codes , then road test again .

 

I thought low fluid might be one of the problems. But when I drained it to take off the pan. I got 5 quarts of it. What amount would be ideal for fluids when draining out? When filling it up again I pumped close to 5 quarts in. At the moment I'm having a feeling it's possibly a bad solenoid.