Ford F150 - 2005 transfer case noise 4x4 hubs unlocked?

I'll be driving at highway speeds then it sounds like the transfer case is trying to go into 4x4 on its own. Loud and grinding noise. I have to come to a stop, then here a clunk and its fine for awhile. Question? Is the front driveshaft supposed to spin in 2wd?

Hey man just had this addressed on my truck this week. It's gonna be a bad IWE solenoid that is a cheap replacement. Not so cheap may be the damage that has been done to the front hubs from grinding those teeth off of the 4WD parts. I had all mine fixed under warranty, thank god. I just had 500 miles left on my 75,000 warranty when this popped up this past Sunday. If you go in to the dealer and tell them about this they should know what you are talking about. Apparently it is a pretty common issue. The IWE solenoid keeps a vacuum applied to your hubs keeping them out of 4wd. When you engage 4wd this vacuum is released. There is some kind of problem with the IWE solenoid and it is loosing its vacuum. Bet you a million bucks its from water contamination.

would that likely be my case too? when i'm in 2wd, here a light rattling/grinding sound, but when i put it in 4x4, no noise at all. i thought for a while i had some sort of engine vacuum leak, but i stuck half my body out the window and could tell it was coming from underneath the truck. so iwe solenoid huh? only had the truck for 2 months so no telling how long its been happening. finally starting to get somewhere though .

How much does the IWE solenoid cost? Have they been redesigned since 2006 to make them more resistant to failing? Wondering if it would be worth replacing as preventative maintenance?

the new part is around $25-30 depending on the dealer, part number for the newer design is 6L3Z-9E441-A , i have an 05 fx4, i called FORD, they said i have a 75k warranty from the factory. so i called the local dealership, they are investigating to see if the IWE will fall under this warranty. will let you guys know what i come up with.

its an easy fix but i want FORD to eat these charges, and i want them to look at my hubs to make sure they werent damaged.