I'm not sure if you found your answer yet, but you do know that your 4x4 system is "on demand" right? The rear tires have to start to spin before the front will kick in. If the wires are in tact and connected to the terminal board as they are supposed to be (barring any other electrical issues or a faulty switch on the handle bars, or problems in the hubs), they should work.
The first time I drove my quad I wanted to test the 4x4 and the salesman had me set it up against a telephone pole and try to spin all four tires (it's a used 1997 xplorer 400). It just dug holes in the rear and then all of a sudden climbed right up the pole

I thought it wasn't working until then.
Just thought I would mention it in case you hadn't thought of that.
-Wes