I just replaced the one on my car, a 1995 Escort, and I'm curious as to how this thing is supposed to work. the resistance across the coil is right, but when I apply voltages to it (anywhere from 8-25V DC) I really don't see anything resembling what I'd expect to see, but I do feel the coil being energized. If necessary I can send it a square wave or sine wave signal, etc., but I can't find anything on the internet explaining how it's supposed to work or exactly what I'm supposed to see. When energised I do some some movement in the parts, but not much. Obviously the part is bad because it fixed my idleing problem immediately when I replaced it, but I'd like to learn something if there is something to be learned before I throw it out.
Note: It had been cleaned maybe a year ago, and so I don't think it was that dirty. Possibly the reason I'm not seeing it do much is because it's broken.