But the four wheel drive doesn't work and the trans is making a whining noise when I let off the gas. The indicator lights on the dash won't come on when the tranfer case is in 4x4. 4 low work, but 4 high does not. I've been told that the "actuator"(vaccum module on back of front axle-dealer exclusive $273 part-) may be the problem. Is this diagnosis correct, before I blow 273 bucks on a tiny part?