1999 Blazer Pushbutton 4x4 problems

My son's blazer has 4x4 problems. The pushbutton switch shows no lights and when you push any of the buttons nothing happens. I checked the 4x4 mini-fuse in the fuse panel but was ok. Any ideas?? He said it was working fine while he was at his uncles ranch dragging downed scrub trees but is just quit working.

Also, I hear a growling noise and feel a vibration when traveling below 5 mph. It seems to be coming from the left front.

Thanks,
Dave

[JaVeRo]

The first thing would be to narrow down where the problem is.

With the wheels blocked, engine running, truck in 2wd mode, reach underneath and turn the front driveshaft. It should turn freely. Push the 4wd hi button and turn the driveshaft again. If it still turns free then the problem is with the transfer case. If it is locked then jack up one front wheel. If the wheel turns free but the driveshaft is still not turning then the front axle is not engaging and it is probably the vacuum actuator beneath the battery tray.

James

Thanks for the reply, James! I will give that a try!
Dave

[JaVeRo]

Post back with the results and I may be able to help. The front axle I am pretty familiar with, on the transfer case I am slightly above lost.

James