Just got a new truck and sold my 04 FX4 to a buddy, it snowed almost a foot today and when he tried to use 4 wheel it wouldn't work. Never had any issues with it. When switched into 4 wheel the light says 4 wheel high and you can hear it click like normal, but doesn't seem to be engaging. While in 4 wheel when you give it gas their is a zing type noise coming from the front right similar to like when a starter spins but doesn't engage the gear. Any ideas what it could be?

 

IWE (Integrated Wheel End) or IWE solenoid? Check out this thread.

https://www.f150online.com/forums/20...replacing.html