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4020 charging system weird problem

M

MaverickM23

Member
Had my 4020 in the shop this weekend to replace some parts. I put new batteries and cables on it along with some hydraulic lines. I also rewired the lights and added the dash light that was missing. Cleaned the starter out and replaced the fan belt. Put everything back together and it seemed to work fine. Then I noticed the fuel gauge wasnt working, checked it and the sender line was touching a ground, fixed that and thats when things got weird. When i fired it back up the GEN light wasnt going out then it got real bright and went out. I looked at the generator and it wasn"t making any sparks inside, then all of a sudden it would but then stopped again. I tryed the lights and the outer lights on the fender stay on but the inner lights and the dash light blink on and off and the fuel gauge pegs to past empty. Turned it off and then switched the key again and had not GEN or OIL light. Then all of sudden they came on. Any ideas on what is going on? I polarized the generator but am thinking something else is wrong with the generator.
 
My gas 4020 wasn't charging good, at least I'd have to charge the battery to run it every month. And that long expensive battery didn't last well.

So I wired in an ammeter. It bounced from peg to peg from a slow regulator so I couldn't tell what it was doing. For just a little more than the price of a new regulator (I'd already replaced and fitted brushes and a new generator pulley to replay the one worn with U groove), I put on a 1 wire alternator. Now I get several years out of the battery, and I went to a side terminal battery mounted on my new step along side the starter. I've not run it in about a year and a half, will probably have to break down for a new battery, its dead now.

Gerald J.
 
That will probably be a 24V system if it is a diesel, so the starter will need replaced also. I would not use one of the delco starters. They do not crank the tractor over well.
 
Must be a 24 volt start diesel?

If so, you are missing the "ground connection" from the midpoint of the 2 batteries to the chassis.

This was typically a pigtail fuseholder containing a slo-blo fuse.

DEERE now supplies a pigtail fusible link, part # R39713.

<img src = "http://i167.photobucket.com/albums/u125/27Grainfield/4020electrical.jpg">
 
24 volt floating alternators have been made, there's several part numbers in the JD 4020 parts catalogs. The original generators were on the wimpy side. 12 volts 20 amp for gas or 24 volts 10 amps for diesel. Intended for a tractor that runs 4 or 5 hours each start, not a half hour like a chore tractor. Can't expect a gas 4020 to run all day on one start while plowing, the gas tank isn't big enough. My 4020 is gas. Many more were diesel.

Gerald J.
 
Yeah I forgot to mention that it is a diesel and 24 volt. I have the ground in place along with the fuse. What doesnt make sense is how the generator goes from creating sparks to suddenly none at all.
 
Do you think thats all it is? It has never done this before. The last time I tryed to get it to work I disconnected the batteries and then reconnected them and re polarized the Generator. But when I did that the Generator made a noise that I dont remember it doing before. Sounded almost like it was trying to turn over.
 
There are two separate feeds on that tractor, one is +12V and one is -12V. The light switch has two sides going into it, and two sides going out. I do guess it is odd that both sides of the switch are bad. Are you sure that both low beams are not burned out? I have a wiring diagram archived and will double check. It is a 24V system?
 
Yes it is a 24 volt system. Once it starts the GEN and OIl light come on then the GEN light will glow very brightly then go out. At the same time the generator has big sparks coming off the brush then it stops. So I try the light switch and the outer lights on the fender are on and the inner lights and dash light blink on and off and fuel gauge pegs to past empty. When engine is turned off and key is switched to on the GEN and OIL do not come on, then suddenly they will and lights work fine without engine running. This all seems odd to me I have been looking things up but coming up short
 
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