I finally engaged my 4wd after a year of owning the truck, when I engaged it I got nothing no light or anything, all I got was grinding from the front end, even worse when I turn and it feels light it's going to snap something when I'm in reverse and wheel is turned. I got under it and check to see if the transfer case was dry but there was some fluid in there, and when I'm driving in 2wd I'm starting to hear a small grinding, which I originally thought we're my brakes. Am I ok driving in 2wd for the time being and does anyone have any thought on what is going on?

 

https://www.f150online.com/forums/ar...then-some.html

 

Good insurance to keeping an active happy 4wd system would be putting it in 4wd every other month for a little bit and just driving across a parking lot or something. Even in the summer months. Don't neglect it and use it only when you need it, use it and keep it maintained.

 

The grinding you are hearing is most likely the IWE (Independent Wheel Ends) trying to engage. The Halfshafts on the front of your truck have the IWE incorporated into the CV joint. The default setting is engaged. Vacuum is applied to disengage them giving you 2 wheel drive. Vacuum failure or water intrusion allows them to engage or partially engage causing the grinding noise. When you engaged 4x4 vacuum was removed allowing then to engage. Either dirt or corrosion has caused them to jam half way engaged. There is a control solenoid on the firewall behind the battery. Check the vacuum lines and the connector.

EDIT Here is a link to how it works.

 

http://www.f150forum.com/f72/how-dia...m-esof-186872/