4020 gen and oil light on dim when tractor is off

Dweitzel

Member
The gen light and the oil pressure light will stay on very dim after the tractor is turned off. It seems that this is intermittent and sometimes the lights are on, other times they are off. If they are on dim, BOTH lights are always on?

I believe the gen and oil light are both on the left battery circuit, but one is on the light switch and one is from the key switch? Any ideas where to start trouble shooting these?

If I disconnect the positive from the RIGHT battery, both will go off. If I leave the right battery connected, the right battery will be discharged after a couple of days.

Sometimes the light switch will light a couple of lights, but most times it does not work any lights.




Any ideas how to start trouble shooting this problem?

Thanks.
 
Off the top of my head two things came to mind, the key switch is shorting internally, or the starter is shorting internally from dust off the brushes as they wear. I don't have my diagrams handy to look at. I will try to remember to come back to this later.
 

You can view wiring diagram for a 4010 here and it will be very similar to 4020 http://www.geocities.com/gwece/deere/. Is ground wire on LH rear battery post to frame intact and has good connections? You can pull starter end cap off starter and check for brush dust without removing starter from tractor.
 
Here is the schematic. Looks like the oil light and the gen light both come off the key switch.

Looks like it could be coming through the starter, starter solenoid, generator, regulator, push button starter switch, or key switch?

Is it possible it is coming back through the light switch through the right hand lights?

I think I can isolate and test the starter, switch and solenoid by pulling the wire off the key switch at the "ST" terminal and that would test out that circuit.

If I pull off the "BAT B" terminal from the key switch, that would isolate the key switch from the left battery.

If I pull off the "A1-GEN" wire from the regulator, and both the oil and Gen lights go out, that would isolate the generator, but if the oil light stays on, then the Generator should not be the problem.

I may want to pull off wire "LT B" from the key switch to isolate the lighting circuit on the "B" side if nothing else tests out as above.

If anyone sees any "holes" in my logic, let me know.
a114864.jpg
 
Its been years since I sold used tractors and all that 24 volt stuff and I didnt remember if that starter end cap was easily removed in place. You and I both seem to always ask about that frame ground connection.

Im headed to Austin for the month of October and I want 70 degree days and cool nights as I will be doing some dry camping!!!!!!!!!!

John T
 
Yes, the ground wire is on the LH battery and connected good to the frame.

I pulled all the wires one at a time from the key switch and the light switch. No change. The 2 lights were still on dim.

I pulled all 3 wires from the Generator. The "A1" wire made both lights go out. Other 2 wires made no difference.

"A1" connects to the middle post on the regulator, and also to the "Gen" light and then to the "Gen" connector on the key switch. Again, unhooking all the wires (one at a time) from the key switch had no change on the lights.

Since "A2" and "F" on the generator had no change on the lights, but "A1" did, it appears to me the generator is the problem? Could the ground (Positive from RH battery), be coming through generator to the "A1" terminal on the generator?

On a side note, I ran the tractor up and down the road, came back and turned it off the the lights are now off?

Any ideas?
 
The genny and VR connections are all across the 24 volt series sum and (if alls well?????) should have nothing to do with frame ground. The reason theres an A1 and A2 is so neither has a frame ground connection like on a 12 volt system with only a single A terminal because the other brush (which would be A2) is grounded.

If unhooking wires and/or road vibration seemed to get things working, Id be thinking of a loose or corroded connection problem or perhaps theres an internal genny problem (brushes, brush holders, field or its splice etc)

These 24 volt systems are hard to diagnose if there armed with a VOM let alone over the internet so sorry, I just cant say sittng here if its a genny or VR or wiring problem, but if shes NOT charging the idiot light is supposed to be on, its sort of like a light wired across the VR's internal cutout relay where if the gennys output (A1 and A2) is coupled up to the battery the voltages are the same so the light goes out.

I DONT KNOW SITTING HERE WHATS WRONG maybe Tx Jim does?? Hes sharp as a tack on these and I havent sold or worked on them for years grrrrrrr

John T
 

24 V charging system problems always gave me fits. Have you checked starter for brush dust?? The brush dust can cause elect system to do crazy things. IIRC the generator fields or brush mounting post can ground out. With wires attached to VR & genny try to isolate genny from mounting bolts.IE hold in your hand. If this tractor was MY tractor and not a collector project I'd spend about $400 and change it to 12 V's. Changing from 24 V's to 12 V's will save you from having a lot of GREY HAIRS.
 
(quoted from post at 07:25:52 05/10/13)

I DONT KNOW SITTING HERE WHATS WRONG maybe Tx Jim does?? Hes sharp as a tack on these and I havent sold or worked on them for years grrrrrrrJohn T

John
You have my 24 V knowledge all wrong. I'm sharp as a "bowling ball" on 24V systems. As I've stated in the past there are other people on this forum including YOU that know more about the 24 V system than me.
Jim
 
(quoted from post at 07:49:57 05/10/13)
24 V charging system problems always gave me fits. [b:bd7f81c85d]Have you checked starter for brush dust?? The brush dust can cause elect system to do crazy things.[/b:bd7f81c85d] IIRC the generator fields or brush mounting post can ground out. With wires attached to VR & genny try to isolate genny from mounting bolts.IE hold in your hand. If this tractor was MY tractor and not a collector project I'd spend about $400 and change it to 12 V's. Changing from 24 V's to 12 V's will save you from having a lot of GREY HAIRS.

How is the best way to Check for brush dust and clean it if it needs to be cleaned??

Can the end plate on the starter be removed and reinstalled on the tractor with out any problems? ie bearing alignment and springs and stuff coming out. :oops:
 

The starter end cap can be removed with starter attached to tractor. The brush holders/springs are attached to starter body. Only difficult thing would be getting the 2 screws started back in their threaded holes. End cap has a bushing in it no brg.
 

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