Gentlemen, thanks for all the replies.
snoranger That's the post I am speaking of, the F150 or expedition. I know this is a Ranger forum but this is where I saw it. I have been chasing this issue for about 3 weeks since I got the vehicle. I have a 2017 Expedition Limited. It has IWE vacuum locking hubs. I have a hum at highway speed in 2wd. Basically Everything works as it should but my front axles turn when driving in 2wd.
This is what I posted in the expedition forum.
To double check the IWE's and the hose leading to them I used the vacuum line at the IWE solenoid to pull vacuum to both IWE's and it held at over 20in for 20 minutes, wheels spin without turning axles, until I disconnected my vacuum pump then the wheels are connected to the axle shaft as they should be. Then I connected everything back and pulled the line off the reservoir, vehicle off, and there was existing vacuum there. So I believe the check valve is working. It seems like everything is working as it should. I even confirmed the front drive shaft is free when in 2wd with the vehicle running by rotating by hand. The problem is I get a noise from the front end when driving, sounds like a wheel bearing. I installed a new motorcraft hub/bearing on the drivers side and the noise is the same. So I mounted a GoPro to the frame and drove around and found out the axle shaft is indeed turning with the wheel when the vehicle is moving and in 2wd. But I noticed that the axle would stop spinning for a second when I was doing a full turn like in a parking lot. And sometimes the axles did not seem to be turning at the speed the wheels was turning. I assume the axles spinning at highway speed is where the noise is coming from. Any ideas as to why the axle shafts are turning if everything checks out?
I did not get any replies from the expedition forum guys then I found Jim's post and it was the same issue.