2003 Tacoma Double Cab 4 cylinder 4x4 Transmission overheating!!!

My 2003 tacoma crewcab's auto transmission runs hot during normal operation and will get significantly hotter (I feel it radiate inside the cab) under hard operation, added an aftermarket oil cooler, did transmission flush all solenoids were tested, wheels are stock in size (although running steel rims), no pinch in the lines...does any one have any idea what might be?

 

Is the torque converter locking?

 

This is my first auto so from what I have read of what locking is, it seems like it is. The transmission will shift normally on an even surface and will remain on its last gear (4th I believe)if I maintain a steady speed if I try to accelerate it will automatically down shift and gradually increase speed. After a shortwhile of being on the road transmission starts getting hot. Gear light has never gone off.

 

I think I would want to hook an obd scanner up to it and see how hot it's getting.

 

I have one Ill hook it up tomorrow and run it to see how hot. I've talked to a few mechanics and only one has considered torque converter failure however the converter is fairly new, could it be that the overheating is due to mistakenly being sold a 2wd converter instead of a 4wd or are they the same?

 

Just on normal cruise slight uphill grade mine sees 200 on a hot day. The temps will fluctuate by 30 degrees easily depending on speed and grades.

 

So I connected the obd scanner and I couldn't find the AT Temp anywhere maybecause I have the cheap one? So I notice a few things, first while on the last gear (4th i suppose) the torque converter doesn't seem to lock when traveling at a constant speed on a flat surface. I notice this after learning how to unlock the torque converter by tapping on the break method. I tapped on it a couple of times and nothing I actually have to let of the gas significantly for it to lock it, but by then its starts to lose power...

Also it seems to get supper hot while stopping and going in the streets as opposed to open Highway.

 

Yeah, I think at temp is one of the Toyota specific PIDs, might not be available on the generic scanners.

If it's never locking, that's a place to start though. How is your gas milage? On my old Chevy when the brake switch failed it kept the torque converter from locking and my gas milage went South