My 02 Ford Explorer 4WD won't work. I have checked it over and found the motor bad on the transfer case so I replaced it and still doesn't work. I found the module, but not sure how to test it. I do know that I have a back feed to the switch in the dash. This switch has 4 auto, 4 high, and 4 low on the switch. I'm leaning toward the module being bad, but the back feed has me confused.