Just got a 2004 Sportsman 500 in with no four wheel drive..Where should I start looking ???

 

Fluid change first,but which model? Two different styles in 2004. One had the awd in the hubs, one had the centralized awd?
Main thing is check that you have power to the grey wire(s) Here's a video for the hub mounted awd that have had problems on ground wires on the awd. If you have the centralized awd,you might try spicing a jumper into the brown/white wire at the front diff to a good ground such as the coil and see if it has awd them. If this doesn't help then it could be a roll cage or armature plate problem. Plus BOTH models have the awd running through the spedo itself. People have also jumped the brown/white at the spedo harness to the brown bypassing the spedo entirely.