I just get trapped in the sand with my F-150,99 "4X4", I was with my kid in the beach and i drove to a dune, I activate the 4X4 with no success, a GMC took me out of there with a rope.

I tried it again in the road and as soon I change the switch to the 4x4 low or high (doesn't matter) the truck looks like the 4x4 is on but the front wheels are not pulling.

The truck seems to have the 4x4 (feels strong) but only the rear axle have the torque.

What could it be? Im thinking on a vacuum hose, but where????

Any help is appreciated, like always.

Ben

 

If your truck has automatic hubs, it's probibly the problem. Try taking them out and cleaning them up, re-grease, then reassemble. One way to check if it's working is to lock it in on something hard, like asphalt, and turn your wheels all the way to the left or rightand see if the truck trys to buck or jump a little bitwhen applying power. Don't do this very much mind you for as they say "this is only a test".