When it rains the wiper motor on your 95 pont transport stops operation except in the fastest position how can you solve this problem?

I would suspect the switch is bad. I experienced such problem. The switch is certainly not bad. The reason lies in an excessive lubrication of wiper motor pinion so that movable electrical points become disconnected from base upon the surface of pinion. You should take off the whole wiper system (I did that myself with no others help so you CAN do), take off the motor cover and electronic board. Underneath it you'll see the pinion. Remove the excessive lubrication and clean two electrical contacts and two tracks with cleaning rag.