Yep,
Connectors are wiring's downfall. I worked for meany years as a electrical system design engineer for an over the road transportation refrigeration manufacture. With equipment that is exposed to the weather and vibration, connectors are always a problem.
My goal as a designer was to eliminate as many connectors as possible. However, for serviceability and assembly, some connectors are necessary.
I hate to say this, but those connectors that JD used on that tractor are about the cheapest and poorest connectors that they could use. Sealed connectors are the best.
Richard