› john-deere-4440-wiringJohn Deere 4440 Wiring Diagram Collection John Deere 4440 Wiring Diagram. Effectively read a cabling diagram, one provides to know how the components inside the system operate. For example , if a module will be powered up also it sends out a signal of half the voltage plus the technician will not know this, he'd think he offers a challenge, as this individual would expect the 12V signal.