Just joined to post this thread hoping I might get some help. I've got this 1998 GMC Yukon 4x4 and it used to have this whining sound that would come on as I turn the key to acc/on position before start, and it'd also last a couple seconds after the truck was turned off. Sounded like a "healthy" sound, but what the hell is it? Now it doesn't do it anymore. Is something going bad? I'd like to keep the truck as long as I can since I'm planning on driving the wheels off this thing. The more I can find out about it, the better.