pplusent

Having issues with my converter not locking up. Has anyone heard of wiring the solenoid to a switch for highway driving? My 93 4runner 3.0 v6 with A340H tranny overheat light comes on every 40 miles on level to hilly roads at any speed over 60mph.
I have a cooler after the radiator cooler, the cooler is rated for a gross weight of 30000lb.
I am not seeing a drop in rpm after it shifts into 4th gear. Solenoids test ok, so I am changing them out tomorrow anyway, but I am thinking the ECM may not giving it the signal.

pplusent

Changed out all three solenoids and no change. Tranny shifts normal through 1st, 2nd, 3rd then forth, at 65mph I level off the engine runs at 2800 rpm and there is no change from there, it never varies. I found the cruse control was not working so I unplugged it, still no change. No codes are being set, so I believe the speed sensor, and temp sensors are working. I believe the ECU is working because the Donner transmission went in to O/D with no problem.
Any Ideas?