Whine is usually caused by ground loops... multiple grounds throughout the car. Try connecting all grounds locally to one access point, if that is a feasible option. Also.. if not an option, make sure that your ground cables are LESS THAN 3 feet long, each. You could always purchase a "ground loop isolator" from Rat Shack, if consolidating the grounds isn't an option.
I would go for the consolidation, first, as it is free, and almost sure to fix you up. (hopefully your grounds are "close" to each other..
HTH
Ray
