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Discussion Starter #1

I've had the 1968 JD 3020 gas synchro shown in the video for about 12 years. She can be a pain in the butt to get running sometimes, but once she is running, she's a happy tractor. It has a completely rebuilt synchro transmission with virtually no miles on it, and a nice little FEL. I use it sparingly for yard work and moving the odd bale.

Right after this video, which was taken when I started her up for the 2019 spring season, I drove it around the yard a few times, pretty happy with myself for getting her running for another year. Parked it in the quonset, went to mow some grass, and noticed smoke coming out of the quonset. Wires had shorted and were white hot fried, wrecking the wiring harness and god knows what else. I pulled the wires off the battery to stop the smoking wires and thankfully nothing burned down. Haven't had time to take it apart and look at it, but dreading the costs of buying a new wiring harness and installing it, and not sure if anything else is damaged to boot.

So, I have two questions:

1) Anyone have any experience with this kind of thing? Tips, suggestions to start?

2) The one thing I note with my tractor is that it is 12v negative ground, but it has the regulator - it hasn't been upgraded to an alternator. I have the reprinted service manual for it, but cannot find a wiring schematic that shows a negative ground for a gas. Most everything I have read or read about online is about positive ground tractors, unless they have been upgraded. Anyone help me with this?

Thanks!

Grant

Green sweater - green tractor
 

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Don't own one but this positive/negative ground subject came up a while back.

Yours by the books...should be positive ground. TractorData.com John Deere 3020 tractor information

Generaters = positive ground in these models "typicly"

Who knows whats been done.

Heres a schematic in this thread of a conversion John Deere 3020 gas generator to a... - Yesterdays Tractors



Id go with the 1 wire chevy type alternater..and patch up what you can of the wires or replace.

Has this tractor eaten battery's in the past?
Has the gas gage worked in the past?


Theres a bit of stuff on YT but not terribly informative ...
 

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Ditto all JD tractors including '68 3020 gasoline were positive(+) ground until 1969 yr model tractors with alternators were introduced
 

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Discussion Starter #4
Thanks fellas,

It's confusing to me as well - I know the details of the tractor and have schematics for what it's "supposed" to be wired like,but...

I'll see if I can throw some pics up once I dig into it - perhaps some visuals will help too.

G.
 

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Discussion Starter #5
Don't own one but this positive/negative ground subject came up a while back.

Yours by the books...should be positive ground. TractorData.com John Deere 3020 tractor information

Generaters = positive ground in these models "typicly"

Who knows whats been done.

Heres a schematic in this thread of a conversion John Deere 3020 gas generator to a... - Yesterdays Tractors



Id go with the 1 wire chevy type alternater..and patch up what you can of the wires or replace.

Has this tractor eaten battery's in the past?
Has the gas gage worked in the past?


Theres a bit of stuff on YT but not terribly informative ...
Thanks for the comments. In terms of your specific questions, it hasn't eaten batteries in the past, and the gas gauge does not work. If I were to guess, the gas gauge is the wrong polarity, because it moves, but it always sits around E.

Given that the wiring harness is $1,000, I am hoping that I can "patch up" whatever I can. I'm not sure if I'll convert it to the alternator but maybe now would be the time, eh? lol
 

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Thanks for the comments. In terms of your specific questions, it hasn't eaten batteries in the past, and the gas gauge does not work. If I were to guess, the gas gauge is the wrong polarity, because it moves, but it always sits around E.

Given that the wiring harness is $1,000, I am hoping that I can "patch up" whatever I can. I'm not sure if I'll convert it to the alternator but maybe now would be the time, eh? lol

I asked about the gas gage because reading elsewhere they only sell 1..its positve ground.

You can reverse the polarity of the generator somehow (polarize?)

Starter is good to go and only spins one way regardless of polarity..(this one is a mystery ) but apparently the way it works.

Ignition coils as I read are wound different to be + or - ground....some say they will work either way??

I'd convert it to normal - ground if you have a bunch of damaged components or wiring....Its a toss-up.
 

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I never did exactly that " 3020 " but the last one I did was an older articulated loader. It caught on fire in a cotton warehouse. How many wires do you need to make that thing run anyway? I used a 7 wire semi trailer light cord for a wiring harness.
Get rid of the generator and regulator. One wire 10 SI, 12V coil with a built in resistor and 12V negitive ground. Add a bolt on breaker or two. That is a KISS wiring harness.
Just my opinion.
 

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For wiring harnesses, I would contact brillman.com . They make original equipment quality harnesses and may even make a harness already modified for negative ground alternator swap. I have used them for 24 to 12 volt conversion harnesses. I hate buy a factory harness and cut it right away to make it work. Less than 1/2 price of Deere's harness. They may not show everything they offer online. Give them a call. If you want fuel gauge to work, you need a sender and gauge from "new style" 3020 that is set up for negative ground.

Also be sure to check the wiring to the ignition coil. If you are using negative ground, The "-" should be connected to the distributor.
 

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If you feel comfortable making your own wiring harness, follow the diagram below. It's a very simple wiring harness and will save a few dollars.


I question a couple of things on this diagram.
1: Do ballast resister systems not normally have another wire on the coil side of the resistor? The other end of the wire connects to the other small terminal on the starter solenoid. It provides battery voltage to the coil while the engine is cranking. This provides a hotter spark for easier starting.
2: Would voltage not back feed from the alternator to the coil when the key is turned off? The engine would continue to run?
The coil with a built in resistor I mentioned changes some what like an electric choke coil. It automatically changes the first few minutes power is to it. Provides high voltage for starts but automatically reduces voltage for long point life. No extra wiring.
 

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If you feel comfortable making your own wiring harness, follow the diagram below. It's a very simple wiring harness and will save a few dollars. /QUOTE]

One problem with your wiring diagram is no allowance for neutral start switch wiring.
You're right........... My bad........... :banghead: What the hell was I thinking. :unknown:
 

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You're right........... My bad........... :banghead: What the hell was I thinking. :unknown:
I was really impressed by your diagram if you made that. It looks factory. Not trying to beat you or anyone else up. It also has no fuses or circuit breakers. Being new to this forum maybe I can help someone and someone can help me. Sometimes reading posts is just educational to me
 

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While in the middle of my post I was locked down. What the hell? Banging my head! I was able to post it. Just trying to share what I thank I know and learn from others.
Will share this true story: My G needed points and I took them with me to the nearest parts store many miles away. The young man at the counter was going through books for a while. He could not find a listing for it. Finally the older guy caved. " Look up a 1946 Chevy ( some kind of car ) with a 6 cylinder and go get them. " Exact match.
We were all the new guy at one time.
 

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No circuit breaker/fuse in wiring diagram is a good catch but IIRC the only circuit breaker on models with gasoline/lpg engines was for lighting circuit.
 
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