Stupid F@*in Tranny!!!

I have a 4x4 95 4Runner with an auto tranny and the stupid tranny wont shift into the overdrive when Im driving. I can go drive it for about 3-5 mins to let it warm up stop, turn the truck off for a minute, take off then it will shift into overdrive. But if I dont stop, I can drive almost 15-20 miles with out the stupid thing shifting!!! And I hate it if I stop and go somewhere for about 30 minutes after warming up, it wont shit again into O/D. Also if im driving on the highway for about 20 minutes doing 60-70, it will kick it out of O/D. Ive already replace my thermostat, powerflushed the cooling system, powerflushed the tranny, and installed an new tranny filter too. All these thing have helped a little but still nuthing. I took it to the dealers, and they say its normal and show no codes. I too pulled out the codes, and no codes show up. WHAT WRONG WITH MY TRANNY!!! :banghead: :crying: :1zhelp: :feedback:

:attention A little help Please?!?!?:attention

Probably your engine coolant temperature sensor is bad. Replace it. The engine coolant temperature determines if the transmission should shift into OD or not. I hope you replaced the thermostat with one with the original opening temperature.

Oh yeah,

I replaced that too. Do you think that maybe my O/D sylinoid/sensor could be too weak?

I would first check the opening temperature of the thermostat you installed with a hot water bath and a thermometer. It wouldn't be the first time it was not correct.

I replaced the thermostat like 3 times already...