i have a 2003 f150. the 4 wheel drive was working fine one day and went out the next and nothing. the light on dash says its in but the tires not pulling. i tried it again a couple days later now it makes a grinding noise before "chunking" into 4 wheel, but still not pulling in the front. any help is appreciated.

 

Shift on the fly or man t-case?

 

It could be one of these things.

1. The electric shift motor on the transfer case is going bad.
2. The front axel vacuume servo is going bad or sticking.
3. No vaccume going to the front axel servo

 

manual in the floor