Noticed today that my 01 SC 4x4 is not working. The transmission does its thing but the front wheels are not locking in. Any suggestions?

 

If by "transmission" did you mean to say transfer-case, and that is working fine. 4x4 light comes on, and front driveshaft rotates. Then you probably have a hub that is not engaging. Without a traction device in the front diff. (LS, or locker), you will have only rear wheel drive. The t-case could very well be engaged, and working properly, but power can't get to the ground via the front axle without proper engagement from both hubs. Check the hubs first.
Good luck.

 

it sounds like a auto hub problem. either replace them OE, or got to a good brand of manual locking hubs. autos tend to get stuck and corrode if there not used, so that would be my guess.