How to tell if 4WD is working?

[maddzz1]

I have an 89 MJ, was moving my truck last night on some ice. My friend was out side and said when my back tires spun on the ice my front wheels didnt move. The day brfore when i used it it felt like it started working (better traction in the snow). Is there an easy way to tell if its working? Maybe see if front drive shaft is spinning, or could front be spinning and 4WD still not working? Thanks

[JohnQ]

You can drive into a big mud hole and if you make it thru it, then your 4WD is working! :D

[Pete M]

Intermittent 4wd is usually a faulty CAD (Central Axle Disconnect) in the front axle. Maybe the vacuum lines are leaking, or the shifter fork is sticking etc. A quick search for "CAD fix" should bring up some of the common ways to bypass the stupid CAD (make sure you click on the button that searches for all words).