B2400 starting problem finally solved

[Gator6x4]

Those things add some voltage drop headed for the trigger of the solenoid but they do not affect the voltage or current on the heavy cable side. Right?

The problem is that insufficient voltage is reaching the solenoid to provide it with the current to close the heavy duty contacts in the starter that are powered by the heavy duty battery cable. The small wire coming from the ignition switch to the solenoid is the wire experiencing the voltage drop. The relay when wired according to the diagram provided uses the voltage, regardless of volts, 9-10-11 etc to collapse the relay sending battery level voltage to the solenoid which provides it with the omp needing to force the two large contacts in the starter together which in turn causes battery voltage provided by the large cable to the starter which in turn causes it to rotate or spin.

how a starter solenoid works - Google Search

 

[JWR]

Sure. Makes sense. I misinterpreted your diagram in the earlier post. Wire numbered 87 goes as it says "to the solenoid" but means NOT to the heavy cable connection into the solenoid, rather to the trigger (primary) side of the solenoid. Duh, of course. ... in that use of an extra relay I see why that would work to trigger the solenoid, not to provide a heavier starting current path from the battery. Among the various posts I think there was confusion about that.

I'm still puzzled as to what we hear clicking when the problem is present. I recall that being a single click (not the kind of repeated click we hear when a car battery is just low...)

 

[JWR]

CADplans, I like the simplicity of just using larger starter cable if that is an answer. Certainly the relay idea just provides more starting current and maybe that is the core issue. I gotta get out from behind this pc and out to the garage and poke into my BX2200... One thing that immediately comes to mind is: Are the starter cables all that small ? The engine and the starter motor are rather small on a BX2200. Wonder also ... Why do we never ever hear of such a problem with automotive cases?

For whatever reason the forum has turned off my ability to edit this post. Maybe that goes off after a day or two? Anyway...

CORRECTION: This post #76 above was erroneous on my part. The relays people are using are NOT to provide more starting current but rather to get an honest 12v to the primary side of the solenoid.


As Gator6x4 has detailed very patiently for us, the root of the problem is degraded voltage at the primary side of the solenoid due to voltage drops in the serial chain of various safety interlocks. That also explains why the problem is occasional and not always present -- because the voltage to trigger the solenoid is marginal and sometimes makes it and sometimes does not. Thus any means to put a full battery voltage to the solenoid amounts to a permanent fix. Now I can agree with the title of the thread -- "starting problem finally solved."

 

[JWR]

So...I finally visited the southern MD authority on all things starter/motor slash electric: Sr. Techn there told me: 1) This click and fail to trigger the solenoid is VERY common. 2) JD has a kit for sale specifically aimed at correcting the issue (as some have alluded to on this thread but I did not see that JD had issued it as a kit intended for this problem.) 3) He agrees that the issue arises because of marginal voltage getting to the primary side of the solenoid. 4) Commented that because the whole issue is marginal (not a big go-no go thing) many different actions affect it. He often takes off the starter, cleans all the contacts and puts it in top shape and that usually makes the problem go away. Says trying to locate which of the several safety interlocks is causing the most of the voltage drop is 'not worth the labor to chase it.' Almost any small 12v relay installed in the primary side for the solenoid cures the problem. He has installed several kinds. AND it is certainly not just Kubota. He has seen essentially every brand of small tractor with the same disease.

 

[Alien]

As a mechanic I can tell you this problem has been around for years on older motor vehicles. A relay was the quickest most economical solution due to ageing wiring and loss of current through a resistance build up over time. Only other option was to run new ignition/starting circuit wiring which takes more time. Tractors are no different.

 

[JWR]

:thumbsup: Yeah verily Mr Alien from down under ! We do need a "Like" button or something on this forum instead of having to do another post just to concur. I suppose you are going into winter soon down there. Hope you don't see too much Chinese virus.

 

[Alien]

Yes, JWR. Still pretty warm here considering it is Autumn. Luckily I live in the 'bush' so I can keep well away from most of it I hope. I think it is going to be a warm winter here.
Still 31.5 deg C.
Cheers

 

[NickAdams]

I added the Deere low voltage relay on my B2400. It has been well over 5 years ago and it still starts every time. Kubmech is the man.

 

[Strummer]

I just bought a B2400 that had the starter issue, after a quick search I found this thread. Just ran over to the JD dealer and picked the AM107421 relay- - -she's starting like a champ now.

Thanks All ! ! !

Going to have to try this fix

 

[MDCKubota]

Since last summer, when I tried to start the tractor, most times it would take up to 10 or so tries turning the ignition key on and off to finally start. With each try, I could hear the starter solenoid click. I cleaned the battery terminals, battery clamps, and ground connection to the frame. Problem not fixed. I then replaced the starter solenoid and that didn't fix the problem. Since I needed the tractor to start without fail for winter snow blowing, I had the Kubota dealer pick it up for repair. He replaced the starter switch and it started OK all winter. This spring, the problem started again. When I used jumper cables to start it, it would start OK. I assumed the 8 year old battery was bad so I replaced it. Problem not solved. I then temporarily installed new battery cables. Problem still not solved. Finally I read Kubmech 's posting on this problem (7/15/04). He explained that the increased resistance in starting circuit as the parts aged caused a decreased voltage to reach the starter solenoid. When this voltage decreased enough, the solenoid did not have enough current to engage. His solution was to install a low voltage relay which would engage and allow full voltage from the battery to engage the starter solenoid. Use of John Deere part AM107421 was recommended (Approx $18). Since I had tried almost everything else (and didn't want to have to send the tractor back to the dealer) I bought the part and installed it. Tractor had sat for about a week and started on first try. The part has been installed for over a week and the tractor has not failed to start on the first try. Installation is easy, it is almost as if this part was made for installation on a Kubota. Wires from low voltage relay plug right into the Kubota solenoid terminals and wire from ignition switch. (See Kubmech 's posting for detailed installation instructions). If you have this starting problem and cleaning the battery cable clamps, ground, battery terminals and your battery is good, I would suggest trying this part. The most you can be out is about $20. Wish I had read this posting earlier, it would have saved me about $350. Thank you Kubmech

When you had the problem starting your Kubota, did the engine turn over but would not start or did you just hear the starter solenoid click? My Kubota BD21F will turn over but it won't completely start. Any suggestions? Any advice you can offer would be much appreciated.