Front driveshaft wont turn by hand
 

Ok, I've searched the forums which only lead to more confusion. Some say the front drive shaft should turn by hand in 2h and some say it shouldn't.... I have an 06 FX4, with auto locking hubs (meaning if I want 4H i turn the knob from 2H to 4H). I've been getting a terrible shake at 55mph (yes I've read the forums on that too, not my question) So I crawled underneath to look at rear driveshaft, u joints, etc..., and by chance I grabbed the front driveshaft to pull myself forward to check out everything else, and it didn't turn......I twisted a little and the shafts going to both front wheels turned. Now shouldn't these turn freely in 2H?....The light to 4H never comes on when I switch the knob, but it is engaged (or else I'd never have gotten unstuck....several times)... Am I stuck in 4H and just didn't know? .Any help would be greatly appreciated.

I get the audible "click" when I turn the knob from 2H to 4H, and "click" again when I switch it back to 2H. Crawled under and wiggled the wiring harness that goes to the electric motor that engages 4x4 and the 4H light came on,flickering.....Just thought I'd add that....

If truck was off and no vacuum to front hubs the hubs are locked. Either use a vacuum pump and try again or start truck and with someone pushing brake for you or parking brake on try turning the shaft and i believe it should turn.

Started the truck, and got underneath. still won't turn. Does it need to be in drive with someone pushing the brakes? I had to do this with the truck in park.... You mentioned someone pushing the brake or setting the ebrake (which doesn't work in my truck for some reason).

if the truck is running you should be able to turn the front driveshaft no matter what position the tranny is in. If you can't something is binding up, maybe you have no vacuum pressure going to the IWEs and they are always locked in or maybe your t-case is stuck in 4wd.

With the truck running and in 2wd pull the vacuum lines off the IWEs and you should be able to feel a slight suction on the end of the hose. To check the t-case drive slow on a hard surface and make a sharp turn if the t-case is locked in 4wd you should feel a lot of binding while you turn.

Took a chance and went ahead and bought the $30 solenoid at autozone on the way to work. Changed it out during my break. Problem solved. Bought the truck in November 2014....hubs probably been engaged since I've had it. 4H and 4L lights both come on now. Since that front shaft has been spinning, it could explain my vibration at around 55mph.....we'll see on the way home from work, I suppose.....Thanks to all for the help