When I try to shift into 4HI, I can hear a sound coming from the front of the vehicle, however, it stays in 2WD. The light on the 2WD button shuts off, but the 4HI one doesn't turn on. 4LO engages fine when in neutral (which is normal according to the manual) Any idea of what my problem may be?

Also, the Service 4WD light is not on, and hasn't ever been.

 

are u sure the bulb on the 4 hi is not blowin, jack up the truck make sure the front shaft is spinning in 4x4 mod. hi and low,

 

I know the 4HI doesn't engage because it spins like crazy just like in 2WD (we just had a huge snowstorm)

 

Left it overnight and now it works fine. Huh...

 

Sounds like my problem,except mine didnt start working!!!!