turn the ignition on, and the switch to high, check for 12v at the positive motor teminal and ground at the negative. Both wires go through the box at the resistor, depending on the year, the neg or pos lead goes through the resistor except on high speed. You can check voltage at the resistor connector without removing the box to know if the fuse/wires/switch are good to the box. Heat is probably important in duluth!