John Deere 3020 Powershift Diesel 24 volt

lanterjm

New User
I have an early model 3020. Just recently I ran into a problem with nothing happening when I pressed the start button. I have troubleshoot numerous issues however I have run into one that I cannot resolve. With the key in the off position, I have power to all the proper terminals on the starter solenoid. What stands out is that the terminal labeled "S" has power to it as well. When I turn the key on, all terminals on the start solenoid indicate power, and both wires to the start button indicate power as well. Initially I suspected a bad solenoid and replaced it. The tractor attempted to start but was a little cold at first. 30 seconds later I pressed the start button again and "nothing." Checked the terminals on the solenoid and once again the yellow wire attached to the "S" terminal indicates hot with the key switch off. Any help would be greatly appreciated.
 
If the batteries are connected "as original", and the connection/fuse/fusible link between the midpoint of the batteries to the chassis is in place and intact, the "S" terminal will read (+) 12 Volts (nominal) with reference to chassis ground when NOT cranking and (-) 12 (nominal) Volts with reference to chassis ground WHILE cranking.

Measuring across between the large terminal on the engine side of the starter "belly" and the large stud highest up on the starter solenoid you should "see" 24 Volts (nominal), with the belly stud being (+) and the terminal on the solenoid being (+).

Check it out and post back.

Be DAMNED careful that trans is in "Park" in case it unexpectedly cranks so you don't get run over!
 
Clutch safety switch, neutral start switch, push button starter switch can all cause problems.
Also their connectors can need cleaning. You can use a jumper made from a short piece of wire
with blade terminals. Jump the clutch switch first. Be in the seat as you try to start.
 
The tractor came from the factory with the positive terminal of one of the batteries connected to the barrel or case of the starter. Is this the way your tractor is wired? If so, hook the positive lead of your voltmeter to this positive cable. Now touch the negative voltmeter lead to the starter terminals and I think they will all read 0 with the exception of the upper solenoid terminal which should read 24 volts as Bob said. Does it? Now with the negative lead hooked to the starter button with the switch on, one side should read 0 and the other 24 volts. Does it? If not check for voltage at the clutch and neutral safety switches. Post back what you find.
 
(quoted from post at 21:29:57 10/28/17) The tractor came from the factory with the positive terminal of one of the batteries connected to the barrel or case of the starter./quote]

If ground wire on LH rear battery post is connected to tractor frame IIRC one can get voltage on all starter posts but It's been many yrs since I tested a 24 volt elect. system.

Positive battery cable doesn't attach to ""barrel or case of starter"" because there's a insulator(key 48) that's intended to prevent electrical connection to case. R11000 Washer - WASHER,INSULATING ADD 2.06 USD

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I should have stopped with the word barrel instead of using the word case. The positive cable(the one not hooked to the solenoid) is insulated from the case as TX Jim points out. However, the little wire from the midpoint of the two batteries to the chassis has nothing to do with the starter circuit whether it is hooked up or not.
 
(quoted from post at 07:50:37 10/29/17) I should have stopped with the word barrel instead of using the word case. The positive cable(the one not hooked to the solenoid) is insulated from the case as TX Jim points out. However, the little wire from the midpoint of the two batteries to the chassis has nothing to do with the starter circuit whether it is hooked up or not.

You're correct about the chassis ground wire not affecting starting circuit BUT it will have an affect on testing the wiring for 12 &/or 24 volts & correct operation of accessories such as idiot lights & fuel gauge.
 
To help sort out some of that below, the small jumper wire from the midpoint where the batteries connect in series to the frame is so some of the 12 volt accessories operate at 12 volts POS with respect to frame/return and others operate as 12 volts NEG with respect to frame/return. Those are the A & B 12 volt feeds. That's to balance the 12 volt loads among the batteries. However,the starter and generator are two wire isolated from frame 24 volt devices and are NOT POS Ground (nor are they NEG ground) as one posted. They operate at 24 volts and ARE NOT USING THE FRAME AS A RETURN CURRENT PATH

Hope this helps

John T Long retired Electrical Engineer
 
Dear Lanterjm, Your question is about a no start condition. The jumper wire between the frame of the tractor and the midpoint of the batteries has ABSOLUTELY NO BEARING ON THE STARTER CIRCUIT WHETHER IT IS HOOKED UP OR IN THE TOOL BOX! Furthermore, when the tractor is running and the generator is charging, current is flowing in ONE DIRECTION ONLY! Flow is from negative to positive if you are a physicist or from positive to negative if you are an engineer. Current while charging is all going one way or the other but not both ways at the same time as in in the misleading pontification described below.
 
Hey there old friend Tom 43 aka Barack aka now erskine (Hey, what's with all those name changes?? You once stated you were banned here or something, is that why???) Congratulations, you're starting to catch onto this electrical theory and beginning to understand pretty well for a retired history professor, you're absolutely right when you say...


"Current while charging is all going one way or the other but not both ways at the same time as in in the misleading pontification described below." DUH Tom, this is DC NOT AC.

As explained for you, you finally got it correct when you stated " The jumper wire between the frame of the tractor and the midpoint of the batteries has ABSOLUTELY NO BEARING ON THE STARTER CIRCUIT WHETHER IT IS HOOKED UP OR IN THE TOOL BOX!

Hey you're doin good Tom, you got two right in a row !!!!!!!!!!! PROVIDED THAT IS you're talking about ONLY the two wire isolated off frame 24 volt starter "MOTOR" and NOT any 12 volt controlled devices, which may use the frame or a return that's dependent on that small jumper wire !!!!!!!!!!!!!!!!!!!! It depends on what you mean when you say "Starter Circuit"


FYI Tom, The purpose of the small jumper wire to frame is to provide the two A & B feeds, one 12 volts POS with respect to frame/return other 12 volts NEG with respect to frame/return for 12 volt devices and loads and THAT HAS NOTHING TO DO WITH THE TWO WIRE 24 VOLT ISOLATED OFF FRAME STARTER "MOTOR". And FYI as you got this so terrible wrong in the past, the John Deere 24 volt two wire isolated system IS NOT POSITIVE GROUND.

Another FYI for a History Professor is that what's referred to as "conventional current" flows from POS to NEG, however the "hole theory" of physics is concerned with the vacancies left behind when an electron is knocked out of its place in the outer atomic shell, so while electrons flow one way the holes/vacancies flow the opposite.

Take care Tom, I hope this helps you and I hope this finds you and your family well, God Bless you my friend

John T, retired Electrical Engineer
 
Mr. T, Your mocking, patronizing attitude does not disguise your inability or unwillingness to understand the series-parallel circuits in the Deere-Delco 24 Volt System in spite of your engineering degree. Perhaps you have been retired too long. Have you considered a refresher course?
 
Gee Tom, I was just trying to help you and educate you as well as all the other fine gents here, I'm here to HELP not feud. Sorry if I offended a good old friend, I certainly meant no harm.

Again take care, best wishes and God Bless you and your family.........

With apologies,

John T
 
(quoted from post at 13:41:52 10/29/17) Dear Lanterjm, Your question is about a no start condition. The jumper wire between the frame of the tractor and the midpoint of the batteries has ABSOLUTELY NO BEARING ON THE STARTER CIRCUIT WHETHER IT IS HOOKED UP OR IN THE TOOL BOX!

Tom
I never stated ground wire(key 30) was required for starting circuit BUT AS I STATED I think if ground wire is attached it will alter VOM readings. PS: JD put ground wire on 24 volt system tractors for a very important reason.
Jim
 
Mornin Jim, as far as your statement " JD put ground wire on 24 volt system tractors for a very important reason"


YOU ARE EXACTLY CORRECT The John Deere Engineers designed the system that way and they were built that way for a "very important reason" which (even as you already know but for others who don't, I will try to educate) I will try to explain.


1) While the two wire isolated from frame ground 24 volt starter "Motor" and Generator operate at 24 volts, there are other devices such as for example say there were lights or gauges or relays or solenoids etc which use 12 volts and IFFFFFFFFF they use the tractors conductive iron frame as the return current path John Deere designed that mid point frame ground jumper wire TO PROVIDE THAT PATH for a tractor that uses the iron frame as the return current path for 12 volt loads.

2) With that center tie jumper wire to frame ground, One battery (or series of two if 6 volters are used) is POSITIVE GROUNDED while the other battery is NEGATIVE GROUNDED.

3 In order to better balance the loads so one battery doesn't have to supply everything that uses 12 volts, John Deere ran two A & B hot 12 volt feeds up to the dash, ONE POSITIVE GROUNDED THE OTHER NEGATIVE GROUNDED.

4) Some 12 volt lights are fed from the POS grounded battery and others the NEG grounded battery (The two A & B hot 12 volt feeds up to the dash).

5) Obviously if two lights one A fed other B fed, were good and conducting current both will still work but like the old series Christmas lights if one burns open (IF THERE WAS NO CENTER FRAME GROUND JUMPER TIE) the current path is broken and NEITHER will work grrrrrrrrrrrr but John Deere didn't want all lights to fail if only one side (A or B) opened. As designed and if the frame serves as the current path WITH THE GROUND JUMPER IN PLACE even if a light fed form the POS grounded battery fails the lights fed from the NEG grounded battery still work. GREAT DESIGN MOTHER DEERE


6) OBVIOUSLY as any 8th grade science student knows, were talking battery powered DC circuits here and current ONLY flows one way not both nor is it alternating back n forth as in an AC circuit. Conventional current as Engineers call it flows from POS to NEG while a physicist may consider Hole or Electron Current as flow from NEG to POS.



7) NOW FOR THOSE WHO DOUBT OR QUESTION MY UNDERSTANDING OF THE JOHN DEERE 24 VOLT ELECTICAL SYSTYEM

DONT TAKE MY WORD FOR IT, READ JOHN DEERE SERVICE BULLETIN NO 268 DATED AUGUST 1958 WHICH STATES THAT BELOW


The Electrical system used on John Deere Diesel ( E l e c t r i c Cranking) Tractors is a 24-volt split-load system using 24 volts for the cranking and charging circuits and 12-volt circuits for the lighting and accessory load.

A 24-volt generator, controlled by a 24-volt regulator, supplies current to carry the electrical load and charge the four 6-volt batteries connected in series which supply current at 24 volts for cranking the engine. The cranking circuit and the charging circuit are two-wire circuits- the entire circuit is carried through wires and no part of it is grounded to the tractor frame.

Two 12-volt circuits are obtained by installing a ground wire between the second and third batteries in the circuit and the tractor frame. Also, the combination switch is in reality two separate switches enclosed in a single housing and operated by a single lever. One of these switches controls current to approximately l/2 of the load, the current being supplied by two of the batteries. The other switch controls current to the remaining 1/2 of the load, current being supplied by the two
remaining batteries



TO THE ORIGINAL POSTERS QUESTION

The two wire 24 volt isolated from frame ground starter MOTOR will operate even if the frame ground jumper wire isn't there or in the tool box WELL DUH HOWEVER if the starter SOLENOID doesn't engage THE 24 VOLT STARTER CANT OPERATE so if it doesn't crank over, test to see if the starter SOLENOID is working

CLOSING now before anyone gets their shorts in a wad or is offended THIS TO HELP AND EDUCATE not hurt anyones feelings and again take John Deeres word for it NOT MINE. AS TX JIM CORRECTLY STATED THERES A GOOD REASON WHY JOHN DEERE DESIGNED THAT MID TIE POINT FRAME JUMPER WIRE and the John Deere Service Bulletin No 268 above explains it. If I'm wrong in my explanation then John Deere is wrong lol. NOTE sure this is for the older 24 volt tractors not the new generation BUT THE FRAME JUMP STILL WORKS THE SAME IN THEORY even if a hard wire was used to carry current versus the iron frame.

REMEMBER The two wire 24 volt starter "MOTOR" doesn't need that frame jumper but a 12 volt load (light or gauge or relay or solenoid etc) that relies on the frame as the current return path JOHN DEERE PLACED IT THERE FOR A REASON (like Jim correctly said) for reasons described above........ ALSO REMEMBER if there's two 12 volt batteries tied in series and the mid tie point is jumped to frame ground as Deere designed ONE BATTERY IS POSITIVE GROUND (supplies around 1/2 of lights) AND THE OTHER IS NEGATIVE GROUND (supplies other 1/2 of lights) and current ONLY flows one way in a DC circuit. Also, the two wire 24 volt isolated off frame ground starter "MOTOR" and Generator ARE NOTTTTTTTTTTTTTT POSITIVE GROUNDED (nor Neg, they are floating)

Best wishes and God Bless all here, I'm here to HELP and to Educate and NOT offend anyone and if you doubt or question my understanding as alleged below READ THE JOHN DEERE SERVICVE BULLETIN NO 268 DATED AUGUST as that agrees with my post IF YOU TAKE OFFENSE OR SAY ITS WORNG TAKE IT UP WITH JOHN DEERE NOT MEEEEEEE LOL.

John T BSEE, JD Retired Electrical Engineer
 
Mornin Jim, as far as your statement " JD put ground wire on 24 volt system tractors for a very important reason"
YOU ARE EXACTLY CORRECT The John Deere Engineers designed the system that way and they were built that way for a "very important reason" which (even as you already know but for others who don't, I will try to educate) I will try to explain.

1) While the two wire isolated from frame ground 24 volt starter "Motor" and Generator operate at 24 volts, there are other devices such as for example say there were lights or gauges or relays or solenoids etc which use 12 volts and IFFFFFFFFF they use the tractors conductive iron frame as the return current path John Deere designed that mid point frame ground jumper wire TO PROVIDE THAT PATH for a tractor that uses the iron frame as the return current path for 12 volt loads.

2) With that center tie jumper wire to frame ground, One battery (or series of two if 6 volters are used) is POSITIVE GROUNDED while the other battery is NEGATIVE GROUNDED.

3 In order to better balance the loads so one battery doesn't have to supply everything that uses 12 volts, John Deere ran two A & B hot 12 volt feeds up to the dash, ONE POSITIVE GROUNDED THE OTHER NEGATIVE GROUNDED.

4) Some 12 volt lights are fed from the POS grounded battery and others the NEG grounded battery (The two A & B hot 12 volt feeds up to the dash).

5) Obviously if two lights one A fed other B fed, were good and conducting current both will still work but like the old series Christmas lights if one burns open (IF THERE WAS NO CENTER FRAME GROUND JUMPER TIE) the current path is broken and NEITHER will work grrrrrrrrrrrr but John Deere didn't want all lights to fail if only one side (A or B) opened. As designed and if the frame serves as the current path WITH THE GROUND JUMPER IN PLACE even if a light fed form the POS grounded battery fails the lights fed from the NEG grounded battery still work. GREAT DESIGN MOTHER DEERE

6) OBVIOUSLY as any 8th grade science student knows, were talking battery powered DC circuits here and current ONLY flows one way not both nor is it alternating back n forth as in an AC circuit. Conventional current as Engineers call it flows from POS to NEG while a physicist may consider Hole or Electron Current as flow from NEG to POS.


7) NOW FOR THOSE WHO DOUBT OR QUESTION MY UNDERSTANDING OF THE JOHN DEERE 24 VOLT ELECTICAL SYSTYEM

DONT TAKE MY WORD FOR IT, READ JOHN DEERE SERVICE BULLETIN NO 268 DATED AUGUST 1958 WHICH STATES THAT BELOW

The Electrical system used on John Deere Diesel ( E l e c t r i c Cranking) Tractors is a 24-volt split-load system using 24 volts for the cranking and charging circuits and 12-volt circuits for the lighting and accessory load.

A 24-volt generator, controlled by a 24-volt regulator, supplies current to carry the electrical load and charge the four 6-volt batteries connected in series which supply current at 24 volts for cranking the engine. The cranking circuit and the charging circuit are two-wire circuits- the entire circuit is carried through wires and no part of it is grounded to the tractor frame.

Two 12-volt circuits are obtained by installing a ground wire between the second and third batteries in the circuit and the tractor frame. Also, the combination switch is in reality two separate switches enclosed in a single housing and operated by a single lever. One of these switches controls current to approximately l/2 of the load, the current being supplied by two of the batteries. The other switch controls current to the remaining 1/2 of the load, current being supplied by the two
remaining batteries


TO THE ORIGINAL POSTERS QUESTION

The two wire 24 volt isolated from frame ground starter MOTOR will operate even if the frame ground jumper wire isn't there or in the tool box WELL DUH HOWEVER if the starter SOLENOID doesn't engage THE 24 VOLT STARTER CANT OPERATE so if it doesn't crank over, test to see if the starter SOLENOID is working

CLOSING now before anyone gets their shorts in a wad or is offended THIS TO HELP AND EDUCATE not hurt anyones feelings and again take John Deeres word for it NOT MINE. AS TX JIM CORRECTLY STATED THERES A GOOD REASON WHY JOHN DEERE DESIGNED THAT MID TIE POINT FRAME JUMPER WIRE and the John Deere Service Bulletin No 268 above explains it. If I'm wrong in my explanation then John Deere is wrong lol. NOTE sure this is for the older 24 volt tractors not the new generation BUT THE FRAME JUMP STILL WORKS THE SAME IN THEORY even if a hard wire was used to carry current versus the iron frame.

REMEMBER The two wire 24 volt starter "MOTOR" doesn't need that frame jumper but a 12 volt load (light or gauge or relay or solenoid etc) that relies on the frame as the current return path JOHN DEERE PLACED IT THERE FOR A REASON (like Jim correctly said) for reasons described above........ ALSO REMEMBER if there's two 12 volt batteries tied in series and the mid tie point is jumped to frame ground as Deere designed ONE BATTERY IS POSITIVE GROUND (supplies around 1/2 of lights) AND THE OTHER IS NEGATIVE GROUND (supplies other 1/2 of lights) and current ONLY flows one way in a DC circuit. Also, the two wire 24 volt isolated off frame ground starter "MOTOR" and Generator ARE NOTTTTTTTTTTTTTT POSITIVE GROUNDED (nor Neg, they are floating)

Best wishes and God Bless all here, I'm here to HELP and to Educate and NOT offend anyone and if you doubt or question my understanding as alleged below READ THE JOHN DEERE SERVICVE BULLETIN NO 268 DATED AUGUST as that agrees with my post IF YOU TAKE OFFENSE OR SAY ITS WORNG TAKE IT UP WITH JOHN DEERE NOT MEEEEEEE LOL.

John T BSEE, JD Retired Electrical Engineer
 
JohnT,
The truth is that the middle wire is for uneven loads on upper and lower side. It is even explained in the 4020 Operator manual that I have!

I had a 5020 24V and the lights were working without the middle ground as it was not there when I bought the tractor and I did not bother... The facts that the lights are working without the ground kills your theory.

The unterisiting things to know is what's happen if you have one light burned and no middle wire? Current probably goes trough the gauge and then trough the only light running (assuming the light is on the other side of the tension)... I assume the gauge has internal resistor that is very high, so little current flows trough the light.
 
(quoted from post at 02:44:50 10/31/17) JohnT,
The truth is that the middle wire is for uneven loads on upper and lower side. It is even explained in the 4020 Operator manual that I have!

I had a 5020 24V and the lights were working without the middle ground as it was not there when I bought the tractor and I did not bother... The facts that the lights are working without the ground kills your theory.

The unterisiting things to know is what's happen if you have one light burned and no middle wire? Current probably goes trough the gauge and then trough the only light running (assuming the light is on the other side of the tension)... I assume the gauge has internal resistor that is very high, so little current flows trough the light.

Please if possible scan & post this statement from a 4020 OM.

24 volt system will not tolerate an uneven load on one of the batteries and I think the little ground wire will be of no assistance in equalizing the load. If an uneven elect. load happens batteries will not charge back correctly with generator. I've also seen 12 volt headlamps on New Generation tractors blackened from getting blasted with apparent higher voltage. Fuel gauge for diesel & gasoline are both the same part number(RE54427) and are 12 volt. I have no idea what "internal resistor or light" you referring to???

As I previously stated ground wire to frame on LH rear battery post is to supply 12 volts to accessories.
 

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