Ok I've got a 65 JD 4020 diesel and it's needed a new generator (or alt. conversion) for a little while, so I've been jumping it off to start it. It usually cranks right up after a little crank on the steering wheel, and has never failed to turn over. But now I havent cranked it up in about a month, and now it won't even turn over. I turn the key on, press the button, and not a sound. Moved the jumper cables to the other battery and still nothing. What should I check?

By the way, I have a reasonable amount of diesel knowledge, but am an absolute idiot when it comes to tractor electrical systems...so talk to me like I'm the dumbest person you know. :o: Thanks.

Do you know if it has a 24 volt starter on it?

Yeah, it's the 24v

try powering both batteries at the same time (with seperate jumping batteries)

I would try putting 12v on each battery, if the batteries are completely dead. I have a JD 3020 on the family farm and we normally have to do that when it won't start. It also has the 24v starter. Be careful because i'm pretty sure you have to reverse the polarity on one of the batteries (put pos. to neg.) but i can't remember which one it is. Hopefully this will get ya headed in the right direction.

Alright, I'll try that. Thanks.

observe the batteries marking on each battery. positive and negitive

Ya when we had a bad battery ours and it did that all the time. Also check that the solenoid on the starter is okay, then tend to go periodically. I used to have to take the cables of and charge each battery individually. That usually worked. Worst comes to worst put it in 7th and pull it somewhere solid and jump the clutch. That always works.