NO VACUUM FROM ENGINE TO 4wd Solenoid
 

I have no vacuum coming from the engine to the IWE solenoid. This is making my hubs stay locked all the time. Can someone help me with where this line from comes from and how to fix this. Which line is the line from the engine, the one with the T in it or the other one?
5.4L V8 2004 New Style

Check out this thread on the IWE system. It should be more than enough information to get you started with troubleshooting. https://www.ford-trucks.com/forums/8...then-some.html

It was a bad check valve but the hubs still will not dis engage from the wheels

Reverse the vacuum lines on the vac silnoid to disengage the front dif
This worked on my 99 f150
Hope this helps

I think on the "new and improved" f150s the vacuum is needed to unlock them

Maybe is there 1 or 2 vac swiches for the front end?
One for engage and one for disengage
How cold is it I have seen the vacuum motor on the dif freeze due to moisture in the system