I've been struggling to diagnose minor power loss issues at low rpms. One of my guesses is that the torque converter is not fully unlocking when it ought to.

There is a torque converter clutch solenoid that governs the lockup. It can be unplugged. Any major concerns if I unplug it for testing? Unplugged, it's likely the converter will stay unlocked constantly. At which point, if symptoms go away, then replacing the solenoid is a potential step. (Failure of the TC itself is somewhat unlikely at lower mileage)

Yes, I know one wouldn't leave it disabled for normal use. Just wondering if I can do any damage. I imagine the transmission D light will flash. I am not clear if the TC locks up on all gears or just the top set, 3-5.

12 Fit sport AT. Mechanic reset TCM but this did nothing. I'm in the middle of a fluid flush 3 changes. Not guaranteed to be a trans issue but this is one line of investigation.

 

I'm going to look up removal for testing by jumping battery voltage and try to see if thats like, possible to do without pulling the trans or whatever. The downside is since it works with fluid even if it could be removed without extensive labor you'd lose your shiny fresh atf.

I read this article, and although it's a freakin headache it sounds like based on operational principle it would not be wise to attempt to run the car with the solenoid unplugged.
It sounds like the purpose of the solenoid is to improve efficiency and protect the transmission, engage tc lock-up, and it's activated by fancy computer junk and as such should throw a series of codes if it malfunctions. in theory it can prevent shifting, rpm change, and even throw the car into limp mode. so testing with it disconnected sounds like a no-go..

it sounds like if your issue is there, it's not functioning optimally, but hasn't fully failed.
Although it's a headache to go back to square one, I'd consider other variables. What led you to thinking this was your fault though?

 

When I say unplugged, I meant the electrical connector can be disconnected. The transmission is still sealed and should run fine simply without the lockup functionality.

It will, for sure, trigger a CEL or at least a flashing "D" on the transmission. The error will probably be some code for "no voltage on lockup solenoid". After all, if the solenoid were to ever fail, it would fail in the "off" position (it is held physically "on" only when power passes through the circuit, in fact that's how you test the solenoid once you remove it, just apply 12V and the valve snaps open).

 

What makes you think that the power loss is coming from the transmission in the first place?