Kubota L3130 7.5a fuse blows

[boobern]

I have a kubota l3130 that keeps blowing the 7.5amp alternator fuse when I turn key to acc position. I was only blowing with tractor running and putting a load on it but it has gradually gotten worse; to where you only have to turn key to acc position. I have checked glow relay(it works) as well as glow plugs(they test fine). It also blew the 50a slow blow fuse. Also tested key switch and panel for short in them but they tested fine no resistance. Any ideas to what it could be? I'm thinking it has to be a short somewhere in the harness between glow relay and plug.:; My reasoning for the short in that direction is because it doesn't blow the 5a panel fuse on the other side of the wiring schematic.
Also off topic but is there and kind of diagnostic tool like obd2 or is that what the codes in dash are for??
Thanks
Adam

 

[mddorange]

:welcome:
To the forum. It does sound like a short in the wiring. Have tested each wire for short?

 

[Dave M7040]

I would be suspicious of the alternator. My comments assume that the voltage regulator is integral with (inside) the alternator.
Disconnect all wires from the alternator, tape them so they don't short against anything and see if the same thing happens. Disconnect the battery ground cable before doing this and then re-connect it for the test. This will avoid any voltage spikes from the disconnection process.
The alternator produces 3 phase alternating current which then passes through a diode trio which is a cluster of 6 diodes which changes the alternating current to direct current.
If one of these diodes starts to fail you can have a short to ground.
If the voltage regulator is separate from the alternator follow the same steps but remove the wires from the voltage regulator as well.
Dave M7040

 

[skyhook]

My guess is with Dave.
The 7.5A is probably the pulse feed for the tach that comes from the alt, the slow blow 50 indicates a
serious short to ground somewhere, could be the alt.
Its hard to tell without a schematic for your machine.

 

[boobern]

Did the same thing Dave said it didn't blow the fuse but red/blue wire coming out of fuse box is getting really hot. Should alternator test short to ground on all posts?

 

[boobern]

Had a 20 a instead of 7.5a in fuse box, changed it and it do sent blow now. Still wondering about alternator and why all three post are short to ground? Thinking what you said about diode is the issue.

 

[skyhook]

Did the same thing Dave said it didn't blow the fuse but red/blue wire coming out of fuse box is getting really hot. Should alternator test short to ground on all posts?

No they should not.

 

[Dave M7040]

I want to be clear on the details. The voltage regulator is inside the alternator?
Where does this red/blue wire go? What size is it.... a large heavy wire or a smaller diameter wire.
No wire should be hot to the touch.
How are you testing the short to ground? with a test light or a multimeter?

Small independent automotive electrical shops can assess your alternator and repair if necessary.
Dave M7040

 

[boobern]

Turns out wire was hot bc 20amp fuse was put in place of 7.5amp. All wires leading to fuse were good no resistance. Tested alternator on vise w/string and drill, it held steady around 12-13 at half speed and dropped quickly at high speed to .7
Also tested doides with multi meter and they tested fine.
Dave-
Voltage reg is in alternator
Using multieter
Red/blue is small. 3 wires meet and lead into alternator

 

[boobern]

Travel speed sensor ended up being the cause of the short. It looked like a stick or something hit the sensor ripping it off. The wires started touching there and completely burnt a red with white tracer wire that leads back to the fuse. Finally took out the glow plug relay and with that out the fuse didn't blow anymore but the wire burnt which was fine because the short finally showed itself. Never knew a short could be so much of a headache..glad it's finally sorted out.
Thanks for everyone's input!