Went to shift into 4 high the light came on but when I was driving didn't seem like I was in 4 wheel drive I stopped switched into 4 low heard it click in and gave it some gas. While I was watching the front wheels they didn't spin on the snow covered driveway. Switched back to 4 high did the same thing with no spin. Any ideas?

 

Is your truck manual or electric four wheel drive?

 

Electric

 

I had the same problem, but i didnt notice till i was stuck in the woods and had to walk.
Drain a little bit of gear oil out of the front diff. and check it. Mine had metal shavings, the gears in front stripped out.

 

Check your vacuum lines also

 

Check and see if the actuator on the axle moves when you shift it into 4 wheel drive