my 4 wheel drive is not working. i put it up on jacks and put it into 4wd. the front drive shaft is spinning along with the rear but the front wheels are not turning. what could be the cause of this. could it be a vacuum or the axle or anything else. also the 4wd light is not coming on if that makes a difference. any ideas? thanks for the help

 

Well wither you have a bad front disco axle (prob the vacuum actuator not doing its job, check the vacuum lines going to and from it), or that front R&P is fried...
Keep it up in the air (all 4 corners), and check the vacuum lines going to the disco (if equipped, it's that weird bump on the rt. axle tube). You can also get a vacuum pump and check if you can manually engage it with the pump to see if it will lock that axle in (just stay away from the tire in case it does start spinning...That could ruin a weekend.).
If not...pull the Ft. Diff. Cover, and inspect the R&P, then fire it up and double check the driveshafts spinning (careful, it could get a bit messy). From there you will see your R&P, and the spiders. If any of those are toast, rebuild the pig.

Like I said, just be aware of of the stuff down under there and out on the sides that will and/or might start moving...