Anybody have this message on a John Deere R4038 sprayer?

It is a 2015 and has been flashing this message since we got it in 2018. It reads that unswitched supply voltage is low and that I need to reduce load or increase rpms. It shows up randomly a hundred times a day while spraying, and almost always shows up when I fold or unfold. When I turn on my lights at night, it flashes the machine and my monitor loses all its mapping and acres from the day. We have cleaned every ground inside and out if the cab, grounded the alternator, and put in new batteries. I have a new alternator to put on but was waiting to see if there was any other suggestions before I eat 700 bucks on something that didn't work