Kubota L3130 - Alternator not Charging - 7.5 Amp fuse circuit has short to ground

PhoenixRising

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Feb 21, 2020
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Hi,
This problem started with my tractor not charging, the 7,5 amp Alternator fuse was blown and the display panel with dark.

I removed the alternator and took it to a repair shop that found the Diodes where burned out. So that is one part of the problem.

However with the alternator removed, and I replace the 7,5 amp alternator fuse as soon as I turn the key on the Fuse pops.

So then I check continuity at the wire harness connector where the Alternator signal wires would would connect ( I believe it is the IG signal) and with the fuse blown/removed, I get a short to ground.

Has anyone seen this before, I looked closely and don't see any evidence of a mouse having dinner on the IG signal wire. It looks like the Instrument Panel and Glow relay and Traveling Speed Sensor and Engine Tachometer Sensor are on the same circuit.

Has anyone seen a problem like this where the alternator going bad takes out other sensors? I am concern that Instrument Panel could be cooked.

Any ideas on where to look next would be very welcomed, I can't attach the schematic I am working with but I believe t is correct.
 

200mph

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Maybe disconnect the wire to the alternator that runs to the 7.5 amp fuse. Does the fuse still blow?
 

PhoenixRising

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Hi sorry for the delay in replying.

Dave and 200mph

The transmission is the HST and it is a ROPS model and yes the alternator is out and the test I did are with the alternator disconnect and removed, the fuse still blows when the key is turned on.
 

Dave_eng

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Hi sorry for the delay in replying.

Dave and 200mph

The transmission is the HST and it is a ROPS model and yes the alternator is out and the test I did are with the alternator disconnect and removed, the fuse still blows when the key is turned on.
As I start to study the wiring diagram, it appears that the glow relay coil is powered by the same 7.5 fuse which goes to the small terminals on the alternator.

Try unplugging the glow relay and see if the fuse still blows.

Dave
 

PhoenixRising

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Feb 21, 2020
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I found it!

Disconnecting the connector from the IntelliPanel (Electronic Instrument Panel) solve the dead short in the wiring. Looks like the IntelliPanel is shorting that circuit to ground. I took the back off the IntelliPanel and the pin 9 of the B connect looks burned.

I guess I will call the dealer tomorrow to see how much a new one is, I am sure they are not cheap,

Any Idea on what could happen?

I wonder if the alternator going bad took the IntelliPanel out? I would hate to install a new IntelliPanel, and fix the alternator and have it happen again.

Thanks for the help.
 

200mph

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Was the burn marks on the circuit board or where the wire connections are within the connector?

I'd consider fixing as it was likely due to a poor electrical joint causing an increase in resistance and therefore heat/temperature until failure.

Kubota: ASSY PANEL, Part # TD060-30205
Part Number TD060-30205
Vendor Kubota
Messick's Price $853.43
Stock Quantity 1
Weight 2.00 lbs
Days to Order In stock
Replaces TD060-30200
 
Last edited:

PhoenixRising

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The burn marks are on the Circuit Board, I only took the back of the Panel off exposing the underside of the circuit board, tomorrow I am going to take it apart further and see if it can be fixed.

I also see the replacement price -- Wow $853.43, I am certainly going to try to fix it and make sure I understand what went wrong before I put a new in.

I will keep you post

Thanks for the help.
 

North Idaho Wolfman

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The burn marks are on the Circuit Board, I only took the back of the Panel off exposing the underside of the circuit board, tomorrow I am going to take it apart further and see if it can be fixed.

I also see the replacement price -- Wow $853.43, I am certainly going to try to fix it and make sure I understand what went wrong before I put a new in.

I will keep you post

Thanks for the help.
Very likely the diodes burning out on the alternator caused a backfeed of voltage to the panel that burned it.
 

200mph

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If what Mr Wolfman states is true, this seems like an overlooked design flaw by the Electrical Engineers at Kubota. Alternator Diodes are known to fail (no big deal), but when their failure results in other very expensive failures this is just neglect by the engineering team.

Since the panel is dead, I definitely would be trying to fix.

Good luck and how about a couple of photos of the intelipanel once removed.
 

GeoHorn

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If what Mr Wolfman states is true, this seems like an overlooked design flaw by the Electrical Engineers at Kubota. Alternator Diodes are known to fail (no big deal), but when their failure results in other very expensive failures this is just neglect by the engineering team.

Since the panel is dead, I definitely would be trying to fix.

Good luck and how about a couple of photos of the intelipanel once removed.
So.... if another mfr’s device, such as a battery let’s say... shorts out and the battery fire consumes the entire tractor... it’s Kubota engineering's fault?
:cool:
 

dochsml

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Very likely the diodes burning out on the alternator caused a backfeed of voltage to the panel that burned it.
I agree. Especially if multiple diodes went, the output ripple AC from the alternator will increase. If the battery can't absorb all of this ripple, it will make it to whatever is looking for power. Seems like something with a circuit board should have a better power input stage (ie: capacitor to shunt this ripple).
 

GeoHorn

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I agree. Especially if multiple diodes went, the output ripple AC from the alternator will increase. If the battery can't absorb all of this ripple, it will make it to whatever is looking for power. Seems like something with a circuit board should have a better power input stage (ie: capacitor to shunt this ripple).
The biggest capacitor possible is that main battery.
 

dochsml

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The biggest capacitor possible is that main battery.
The battery is not a capacitor. While a battery can absorb some amount of AC ripple from a faulty voltage regulator, it has a high internal resistance unlike a capacitor. You need the low internal resistance of a capacitor to shunt ripple back to it's source.
 

200mph

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So.... if another mfr’s device, such as a battery let’s say... shorts out and the battery fire consumes the entire tractor... it’s Kubota engineering's fault?
:cool:
These are two different scenarios. The one I'm referring to is with products they specify and are well aware of the common failure modes within the product itself. Failures like this hint at weaknesses within the product development cycle and the engineering decisions made along the way. A simple FMEA or similar technique should have prompted the discussion what happens when a subsystem fails and resulting action.

These type of discussion take place on a continual basis within world class companies. Some are more customer concentric than others.

Perhaps they discussed it and elected to do nothing. Lets face it, they have very little incentive to improve their product. As long as it makes it out of the short warranty period, they are golden. Even when there are issues within the first year, enough people take it upon themselves to fix because of the hassle to return to dealer.

It's ok if you disagree.

Have a great day!
 

GeoHorn

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I’m not trying to be disagreeable at all. But I can testify that one of the sure-fire ways to fry an alternator/regulator and creat related electrical failures is to run a system with the main battery disconnected. The reason is because the battery acts as a large “shock absorber” for the system when spikes occur.
The same thing occurs (electrically) when the battery has a poor or intermittent ground or corroded terminals. This defect is well-known and often cautioned-about in operator manuals.
 

dochsml

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Jan 21, 2020
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I’m not trying to be disagreeable at all. But I can testify that one of the sure-fire ways to fry an alternator/regulator and creat related electrical failures is to run a system with the main battery disconnected. The reason is because the battery acts as a large “shock absorber” for the system when spikes occur.
The same thing occurs (electrically) when the battery has a poor or intermittent ground or corroded terminals. This defect is well-known and often cautioned-about in operator manuals.
What you are saying is absolutely true, but I didn’t catch where the OP was running without a battery. I thought they were switching key on with battery and no alternator? I don’t know how Kubota charging circuit is wired, but the alternator probably won’t output with battery disconnected.
 

PhoenixRising

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Feb 21, 2020
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The sad finally -- So here is the conclusion to this problem as I see it.

First to clear up a few comments made above,
1) The battery was connected at all times,
2) discussing this problem with the shop that fixed the alternator, we believe that one half of the Diode Bridge failed and that created a voltage spike that fed back to the panel and fried it.
3) I do believe it is a poorly designed IntelliPanel, if not from the standpoint of being fault-tolerant and being able to tolerate the diode problem, then from the standpoint of having so much function in one component of an electrical system that failure of that component cost $850. Which is what I just paid for a new panel !!!

Here are some additional details of the problem, from the schematic I have which is out of the Kubota “WORKSHOP MANUAL TRACTOR L3130,L3430,L3830, L4630,L5030 ([3] HST MODEL) page 468” dated November 2003.
The 7.5 amp Alternator circuit (and the IG signal from the Alternator) connects the IntelliPanel to Pin 9 of the “B” connector show on this schematic. In my case checking continuity Pins 9, 1, 2, 3 are also connected and I believe this occurred when the voltage spike occurred, Pin 2 is a ground which causes the Alternator fuse to continue to blow when the IntelliPanel is installed and the key is turned on. (one note this pin numbering is form the schematic the circuit board numbering is different)

I thought about hacking up the circuit board to bypass this failure, but then I figured I would end up with a $15,000 tractor with a screwed up and unreliable display panel, so I did what an older gentleman once told me “Sometimes you have to belly up to the bar and eat the Reality Sandwich” meaning, in this case, go to the dealer and pay the money for a new panel, which I did.

The new panel should be here in a couple of days, I will post when I get it all back together and confirm that it works. I posted pictures of the circuit board and indicated the problems in the blue marker. (well I tried uploading the picture and the system gave me an error, I will try again later today)

I hope this helps someone in the future.