Toyota Repair: 91 4runner, air flow meter, fuse box

Question
I m having a automatic trans overheating problem.In about 15  minutes over highway driving the trans overheats.I looked underneath and found a blue and white wire unplugged,traced it out and it looked like it went to a fan on the passanger  side of radiator.I m assuming it s the trans cooler.I need to know if the fan should be turning at a high rate of speed,which it isn t.Also could you tell me exactly the process of cooling the trans.I m better than average with  my tools.Thank-You,Mike it s a 91 4runner 4x4 automatic transRe:Thank-you for the answer...In my quest of tring to figure out my problem a friend told me to bypass the electrical and supply power straight to the fan in doing so I applied power to wire that goes to a sensor of some type on the transfer case and goes into a harness to the fuse box i guess.After doing this stupid thing my car will start and idle but as soon as i give it gas in park it wants to die and bogs down to almost killing the engine.Sometimes i can get it to rev up and sometimes it won't the exhaust smells as if it's getting to much gas.I replaced th efi relay checked all fuses checked the volume air flow meter and all seem to be good.I checked the timing it was right on.So by applying power to that wire i know i fried something.The color of the wire is blue and white and like I said it goes to the transfer case.The plug connector is broken and it keeps coming apart thats why I thought it went to the fan on the radiator.Could you also tell me what that sensor does.I'm really not an idiot,most of the time.Anyways the reason I think the trans overheats is the atf light comes on and when that happens it spits fluid out like crazy then when it cools off no leaks whatsoever.I just bought the 4runner so i know nothing about them,but as u can see thats obvious.Thanks so much,Mike

Answer
There is only one switch that I can see on the transfer case and that is the transfer indicator switch but the wires are pink/green and black/white, are you sure the wire you applied 12 volts to was not black/white because this is a ground wire, by the way neither has anything to do with the a/c cooling fan, it's controlled by an entirely different circuit and this fan does not cool the transmission, the transmission is cooled through a passage in the lower part of the radiator so the engine cooling fan and the engine cooling system is responsible for cooling the ATF.
Make sure the engine is not overheating.