I have a 2007 F150 Crew Cab with electronic four wheel drive sometimes when I am driving the four wheel drive tries to engage which makes a horrible grinding and loud noise. If I slow down or put it into four wheel drive high it will engage and quit. I have jacked it up on the lift and checked the front end, transmission and transfer case levels and they were all ok. Any one else ever have this issue?

 

I haven't worked on the newer 4x4 hubs. but they are vacuum operated and are prone to vacuum leaks at the vacuum valve that I believe is located under the battery. Check that for a leak(s).