1990 Volkswagen Passat Car stays in 2nd gear at all times.

I recently purchased a 1990 VW passat GL, really cheap and the car runs great, the problem that I am having is that when the car is put into drive it starts out in 2nd gear and will not start out in 1st and will not shift into 3rd it seem to be lobed in 2nd for everything. Guy that I purchased the car from informed me when I bought car that this is the same problem that he had. He believed that it was an electrical problem. What do you think? Could it be a transmission shift sensor or modules and if so where is it located and how can it be checked out.

He said that A transmission shop checked it and they could not figure it out either, they guessed an electrical problem. I don't want to put alot of money into this car if no need be.

Thanks