4020 wiring

MikeinKy

Well-known Member
I have a 1966 4020 powershift that was a gasser. it now has a 404 diesel. Apparently, it was pos. ground. I want it to be neg. When I connect the wiring I have a dead short somewhere. I haven't connected the alternator yet. I connected the pos. bat post to the starter and grounded the neg post of the battery. Then connected the starter button wire to the small starter terminal, wires from the circuit breaker that supplies current to the switch are to the large starter terminal. When I push the starter button it smokes and trips the breaker. Any ideas?
 
My bet is it's something simple that your missing, it was a neg gound system to start with.
 
Couldn't really tell the polarity. I bought it with no battery and it hadn't been used for over 15 years. I was looking at MR. Thinkers almanac and it sorta insinuated that they were pos. ground unless they came out with alternators. I didn't really know. I'm sure it's simple. That's the stuff that bites your butt. I asked you questions about it a couple of weeks ago. I appreciate the info. I put in a 4430 engine, and I got it started today. Now am trying to sort out the wiring. thanks for any help.
 
I have found that I can make a new wiring harness easier than I can repair an old mess.Unless your harness is in great shape you might want to consider that option.
 
Wiring is in pretty sad condition. It would be easy except for the idiot lights. I'm not sure how to get them to work correctly. It just has two, oil and amps. That and the fuel gauge.
 
Mike, your tractor was in fact a positive ground system when it left the Waterloo factory. Tim just made a typo.
 
(reply to post at 06:34:14 02/24/14)

I agree in the fact that a 4020 gasoline was positive ground from factory but it's very easy to change to negative ground. I think your tripping circuit breaker problem is frayed insulation on a wire or "short in starter". Have you checked amperage draw of starter?Does your tractor have a starter relay above starter? I posted a photo of utility tractor relay but the principles the same.
mvphoto3934.gif
 
Far as I know:

ALLLLLLL Two Cylinder gas Deeres were originally POSITIVE GROUND

The New Generation 12 volt tractors were POSITIVE GROUND as long as they still used Generators but switched to NEGATIVE GROUND once they started using alternators.

Contrary to what has been incorrectly posted here, ALLLLLLLLLLLLLLL 24 volt Deere Diesels WERE NOTTTTTTTTTTT POSITIVE GROUND but instead were a floating two wire 24 volt system in which the Starter and Generator were electrically isolated from frame ground (at least according to John Deere Wiring Diagrams and Service Bulletins including but not limited to SB 268).

NOW if you had a Generator, it can work at EITHER Pos or Neg ground once polarized and other things such as coil polarity and ammeters etc. HOWEVER with an Alternator IT NEEDS TO BE WIRED TO MATCH THE ALTERNATORS POLARITY and many are Negative Ground and if that's so and the alternator uses a frame ground electrical connection then Neg Ground it is. Still ignition coil polarity and if had any ammeter are polarity sensitive and may or may not need attention.

John T
 
Mike,
email me at Charles.whitlock at Hotmail.com and I will send you the complete wiring diagram for both versions of early diesel 4020. it is not hard to completely rewire a 4020 diesel. It does take some time if you are doing it from scratch but it isn't a bad job to do.
 
What starter is in it now? That is the only item I can think of off the top of my head that would short you out right now. If you have the 24v starter then it is your problem and I would find it a new home.
 
(quoted from post at 12:19:12 02/24/14) Mike,
email me at Charles.whitlock at Hotmail.com and I will send you the complete wiring diagram for both versions of early diesel 4020. it is not hard to completely rewire a 4020 diesel. It does take some time if you are doing it from scratch but it isn't a bad job to do.

Your 4020 "diesel wiring diagrams" will be of little help to Mike since he has 4020 "gas wiring harness" on the tractor.
 
Jim

They will help him if he wants to redo it and it is possible who ever converted it also converted the wiring. After all it isn't a gasser any longer. I am trying to actually be helpful here, not just sit here and try to p**s on others while really not doing anything to help him. Seriously, wth is up with comments like yours?
 
And another thing Jim, he did say
"Wiring is in pretty sad condition. It would be easy except for the idiot lights. I'm not sure how to get them to work correctly. It just has two, oil and amps. That and the fuel gauge."
and my diagrams would most certainly help with that. So it looks to me like my diesel wiring diagrams are helpful and appropriate in this case. Help people and drop the attitude or go away.
 
(quoted from post at 17:15:09 02/24/14) Jim

They will help him if he wants to redo it and it is possible who ever converted it also converted the wiring. After all it isn't a gasser any longer. I am trying to actually be helpful here, not just sit here and try to p**s on others while really not doing anything to help him. Seriously, wth is up with comments like yours?

MikeinKy stated the tractor originally was a '66 gasoline model. I still think 24 V diesel wiring diagram will not be that helpful but I wasn't trying to step on your toes. Gasoline wiring harness doesn't consist of batt A & batt B circuits such as diesel wiring harness so I think trying to rewire a 12 V tractor using a 24 V diagram will make things more difficult.
 
The 24volt diagram barely changes to become a 12neg ground diagram. The diagram I have also comes with the complete conversion instructions and a text file of helpful part #s and suggestions from me. It is the same I have given to about 20 people on this forum who have emailed me and requested it after finding my original post about it. We can each have our own opinions but I really do think the diagram will do more to help him than the picture of a utility tractor relay, especially if he decides to rewire the tractor. It is not hard to rewire a 4020, premade wiring looms make it faster than doing it from scratch (mine is made from scratch). Either way you do it, a wiring diagram and instructions will come in extremely handy. I might go pull my tech manual and look, but I really doubt the gas diagram is much different than a converted diesel one. The only difference should be the wire from the key IGN to power the coil/spark plugs. There is nothing else in the circuits.
 
In reference to the Bat A and B, your are correct, when converted the Bat A and B are twisted together at the alternator and down at the starter fusing them into one circuit. Its not hocus pocus, remove the regulator twist the wires, install a diode, install new starter, install a solenoid and you are done, the conversion to the is that simple as are the changes to the diagram.
 
I just pulled the TM. The diagrams are not much different between the two. The Bat B wires are there, just not used according to this. According to this, it uses the same key and light switch. If it is really that big of a deal to you Jim, I can send him a picture of the "spark ignition" diagram as well.

What it all boils down to is that it doesn't matter what he used to have, but what he needs to have now and that is a 12v neg ground wired 4020 diesel.
 
(quoted from post at 19:40:43 02/24/14) If it is really that big of a deal to you Jim, I can send him a picture of the "spark ignition" diagram as well.
.

4020_1966
I never insinuated there was any hocus-pocus involved in changing a 24 V harness to operate on 12 V. I don't really need you to send me anything as I think I understand a JD 24 V fairly well at least better than the average person. If you think that the utility relay kit I posted a parts photo of won't work just fine on a 3020 or 4020 with a 12 V system you're not hardly the JD electrician you think you are.
 
I put a denso starter on for a 4430. I think I will do away with the warning lights and use gauges. I also need to add a remote solenoid to activate the one on the starter. I think that's the real problem. Thanks for the help guys.
 
(quoted from post at 21:40:31 02/24/14) I put a denso starter on for a 4430. I think I will do away with the warning lights and use gauges. I also need to add a remote solenoid to activate the one on the starter. I think that's the real problem. Thanks for the help guys.

Nippodenso starter are very goo starters.
Here's a photo of the starter relay kit for a 4020 >sn 201,000 with the part numbers. You get just the relay from JD.
RE164448 Starter Relay ADD 25.37 USD
or the complete kit with instructions.
RE44536 Starter Motor Kit ADD 143.58 USD
mvphoto3980.gif
 

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