Windshield Wiper/washer Linkages problems of the 2000 Ford Excursion

Wife driving children to school, wipers unknowingly frozen to window and wipers unknowingly on intermittent cycle, wipers finally unfrozen and moved, meanwhile smoke filled the cabin, smelling like soldering fumes. Turned off wipers and smoke stopped. Later, tested wipers, and they would not stop. Took vehicle into dealer, and had a pending recall repaired, at the same time we had to have the multifunction switch replaced, and wiper motor replaced. Dealer service technician advised that gem module was functioning correctly, but smelled like it was burnt, and might need to be replaced in the future. 7 days later the wipers did not work again. This time there was no indication of problem, mother and children drove into a blizzard, and found that wipers would not function. Luckily it occurred in a place that was not busy, and they were able to safely get off the roadway into a relatives driveway. It could have been very bad had it been on the freeway, in driving rain/snow/slush. Now I'm sure the dealership will be telling us the gem module will need to be replaced, completing the entire wiper system being faulty within 1 week's time for the second failure ( on 1/15/2008). Question: how would the technician know that it smelled like the gem module was burnt, unless it is a known problem? how does the entire wiper system, from control switch, to control module, to wiper motor go bad all at once?.