A slightly more useful fix for those with tuners in their cars (but not at home) might involve Kim Covil's tuner detection patch. If a tuner is found, it forces DC mode, otherwise, AC mode. I used this with excellent results for a brief period of time when my AC adaptor flaked out. The benefit above the Force DC mode is that it's automatic. Drawback is, of course, it requires that you have a tuner in your car, and no tuner at home.