Sounds like a pump or other hydraulic issue. I'd raise the front end off the ground, and with the truck running have someone turn the wheel from side to side, with no pressure between the tires and the ground it should move easily. If it is hard to turn watch for any shaking or jerking of the pump. Then turn the truck off, leave the key switch on and see if it has the same resistance to turning. If it turns easily with no problems while raised off the ground with no power assistance it isn't a problem with the front end components, but is within the hydraulics. Something is restricting the flow of fluid, and that something could be a bypass valve in the pump.
Last edited by Keith_B; 01-31-2010 at 06:55 PM.