Yesterday's Tractors - Antique Tractor Wiring Basics Wiring Basics by Curtis von Fange. One of the most neglected parts of old tractors is the wiring. After sitting in the elements for half a century or more much equipment wiring has deteriorated to sparsely covered strands of copper or other metal. Small Engines - » Basic Tractor wiring diagram This is your basic tractor wiring diagram. There are entirely too many different setups to even begin drawing or posting all of them on this website. The above diagram will give you an at a glance idea of how a tractor is wired up. The more bells and whistles on a tractor, the more wires and switches and relays.