Mitsubishi Repair: Gearbox galant 1.8 twin cam 1990, problem occured, failsafe

Question
Hello,

I've bought a galant a while ago and during a drive the gearbox shifted down from 3rd to 2nd and up again and down again to be stuck in second gear. The next morning all was fine, but after a while the same problem occured and now the box is stuck in 2nd gear. I replaced the gearbox with a working one and that did not fix the problem.
2nd gear works, revers and neutral but that is about it. Is it the computer or could it be a sensor and where is that computer located and where is the sensor ( is there only one sensor ? )
I just had the car for a diagnostic readout, but they could not read this model.

I disconnected the battery to try and get the computer out failsafe, but that does not work. I hope it is just a sensor.

Thanks in advance !

Niels

Answer
Niels: I would say if you replaced the gearbox and that did not fix the problem. That it would be your computer. You know don't you that Mitsubishi farmed out the building of their computers to another company which did not build very good ones. In that a piece in the computer will start to leak into the computer and with time it kills off the computer. You could buy yourself a repair manual for your car most parts stores have them for around $20.00. You then could get a voltmeter, using the repair manual to know what readings you should be getting. You could check to see if there is any sensors out or if it is your computer. I can name off many sensors that control the shifting of a transmission but it could be anything at this point. Have you checked the transmission fluid and how old is the filter? Sometimes if you change the fluid, put in a new filter and then some reconditioner made for the transmission it will help a lot too. You can get the reconditioner at any parts store for around $16.00. Have you checked the fluid what color is it? Pink or kind of pink color. Or is it black or brown, does it smelled burnt? The computer for your car I believe is in behind in the glove box. Or it is on the side of the glove box. Remember now if you replace that computer to make sure you get the right computer for your and engine. I have had people write to me, that borrowed one from a friend or else went out to a junk yard and got one there. But still nothing worked, you must get the right model of computer for your car. If it turns out to be the computer, you could also have the computer rebuilt too. A lot of places on line say they can do that for a fee. I hope this helps and good luck! Linda