A 4020 john deere tractor to a 12 volt system.diagram Oct 11, 2011A 4020 john deere tractor to a 12 volt system.diagram trying to convert a 4020.. trying to convert a 4020 john deere tractor to a 12 volt system anyone give me a diagram of what to do or something to go by. Replaced all wiring harnesses. Got Kit from John deere, starter, sylonoid, the whole works. Related searches for john deere 3020 12 volt wiring diagram john deere 3020 wiring diagramjohn deere 3020 wiring schematicjohn deere 3020 battery wiringjohn deere 3020 battery diagramjohn deere 3020 electrical diagramjohn deere 3020 starter wiringjohn deere 3020 wiring harnessjohn deere 3020 parts diagram