i have tried 4lo and 4hi and neither of them work, the button says its engaged but i only get rear tires spinning on gravel. any ideas?

 

Sounds like a vacuum problem. But this has been talked about many times, if you search "4x4" you will get everything you need to know about what to check. I would link you to some threads but I can't on the mobil site. Or maybe try searching "4x4 problem"

 

Check out the Tech Article (DIY) Index link found in my signature below. It's covered in there.

 

i pulled the battery and tray out and tested the vacuum thingamajig
vacuum activated 4wd - YouTube
so, naturally i was excited it wasnt that. i was just curious because i havent even tried to use 4x4 in awhile and went down the block put it in 4hi and it definitely engaged so i started driving, i pulled into a driveway and could feel the resistance in the steering so its working right?

 

If you feel resistance while turning on a high traction surface, then the system should be engaged.