Auto hub not locking in...

[182Ranger]

I had my '98 in at work today to see if my front tires would spin when I engage 4 wheel drive. It has auto vacuum hubs and electric transfer case. I put it up on the hoist and put it in 4. The front tires wern't moving, although my front driveshaft was, and light in dash says it was in. It does this for both 4 high and 4 low.

Can this be simple as the vacuum line leaking going to the hub itself, or just the hubs aren't engaging properly? Also, if possible, is there a way to see if the hubs are good or bad? I'm sure I'm just like everyone else out there...I don't wanna throw parts at the thing and hope the problem diisapears.

Any help at all would be appreciated. Thank you.

 

[4x4junkie]

If the axle half-shafts are turning, but the wheels are not, it's definitely an issue with the hubs not engaging.
Could be a plugged line, but far more common is the hub itself has failed.

There's some tips in the Tech Library for modifying the hubs so you can either work them manually, or lock them in permanently. You could also swap to a set of aftermarket AVM manual hubs which should take care of the issue as well.

http://www.therangerstation.com/tech_library/AVM_hub_swap.htm
http://www.therangerstation.com/tech_library/99hubswap.htm
http://www.therangerstation.com/Magazine/Apr04/offroad.htm