4 x 4 fuse keeps blowing
 

I have a 2002 Sport trac 4 x 4 and every time I turn the switch to 4 x 4 high or low the fuse blows. Any suggestions as what to look for other than an electrical problem? Someone at my work suggested the solenoid in the hub may be stuck causing the fuse to go. What do you think? I would appreciate a quick check and fix if you have one.
Thanks in advance,
J.

Since you have to start someplace, unplug the plug from the shift solenoid/motor on the transfer case and see if the fuse still blows. If it does there is a problem in the wiring. If it does not there is a problem with the parts on/in the transfer case.

Thanks hanky, quick update,
Before when I replaced the fuse the 4x4 would work for a little bit and then the fuse would blow. Now when I replace the fuse nothing works at all. I also need to find where the plug is for the transfer case. I've read the control module is behind the glove box and was wondering if that may now be shot? With nothing working I'm not really sure how to proceed.

A good portion of the time the electronics are pretty dependable. Why not reinstall the module ,unplug the solenoid plug located on the transfer case , then put the new fuse in and see if it stays intact. You gotta go under that vehicle one way or the other. Just follow that rear driveshaft up to the front of the vehicle and where it connects to a large assembly that has another driveshaft going up to the front of the vehicle. On that assembly you should see some electrical wires with a plug. Carefully unplug it then try installing the fuse and see if it blows.