This is a problem that started a couple months ago and now that it's finally getting warm again, it's time to fix it. Basically, my windshield wipers will only work if I set the switch to low or high speed. The wipers do not work at all in intermittent mode. From what I've read, the problem seems to be either the multifunction switch or the timer module but I'm not sure which I should be looking at. I had replaced both parts a few years ago in an attempt to fix a pesky "No bus" problem, which was ultimately resolved after replacing the timer module. I've got a rocky history with O'Reilly parts but can't rule out the used timer module (can't buy those things new apparently). Problem is, I don't know which one I should be looking at and neither of those parts are cheap. Got too much stuff going on to play the old "swaptronics" game. Is there some kind of diagnostic testing that I can do to isolate the problem?