New guy. New problem

[badpaddler1980]

Hey guys! So I am having a problem with a John Deere 250. Went to start it, and as soon as you turn the key it is blowing the fuse. I am seeing that 2 of the wires going into the back of the ignition switch are toning to ground. Bothe end up going to a junction of a bunch of yellows. It has no Auto preheat, no high flow, so I know it is not those. I did however find a relay (that is not in the manual), with wires going to it 740AA, 740AB etc. (That are also not in the manual), and a strange red what looks like a jumper (but doesn't tone that way). I cannot figure out what these devices control. The 12VDC is definitely direct shorting. Does anyone have an idea do what to look for?

 

[mrbb]

OK< lets start here,is this a new issue?
as if you owned this machine a while and it worked fine
but now you have this issue!

IMO< odds are the new issue might be rodent related,, or just a wire rubbed thru some place on you,
causing a short which is blowing your fuses!

SO, I would maybe suggest simply back tracking wires and looking for any with damage
some times its the common issues we skip thinking its something bigger

but this is where I would start looking,
now if you just got this machine and its has issue since you got it, well, that is another story maybe??
but I would still back track wires on blown fuses, to rule that out before going on wards!

 

[badpaddler1980]

OK< lets start here,is this a new issue?
as if you owned this machine a while and it worked fine
but now you have this issue!

IMO< odds are the new issue might be rodent related,, or just a wire rubbed thru some place on you,
causing a short which is blowing your fuses!

SO, I would maybe suggest simply back tracking wires and looking for any with damage
some times its the common issues we skip thinking its something bigger

but this is where I would start looking,
now if you just got this machine and its has issue since you got it, well, that is another story maybe??
but I would still back track wires on blown fuses, to rule that out before going on wards!

Completely new issue. Ran it one day. Was fine. Next morning, no start. Checked for signs of rodents but everything looks good. Problem is not being able to find that relay (or other weird red connector) in the manual, I have no idea where those wires go.

 

[mrbb]

well like I said, best bet is to follow wires back from relay/fuses
if problem just started, odds are high its a short in your system, and over time things wear out, ,. rub thru or again mice

it can be a pain to follow wires, but its what needs to be done to rule this out!
doesn't take much to cause a short

 

[badpaddler1980]

I feel that. Do you by chance have any idea what this relay (and more curiously) the small red tab are?

 

[badpaddler1980]

I think the red one is a diode, but the unit does not have High Flow, so it isn't that (and the wire colors/numbers don't match with the manual). Same with the really. Those wire numbers are not found anywhere in it.

 

[mrbb]

I have no real clue what the relay is exactly for, or even if its original, or added on later
like maybe to run a flashing light or something, a previous owner installed

But again if it ran Ok before, I doubt its your issue at hand now!

 

[SkidTracks]

Did you find what was causing fuse to blow?

Black cube looks like a relay.
Red tab looks like a jack & Plug.
Plug could be a rectifier to stop relay's coil from spiking circuit when de-energized. Or plug could be for disabling relay. Another possibility is plug is LED indicator light (relay on/off or contacts open/closed).

 

[badpaddler1980]

Traced it all down. It turned out to be the cold start relay on the bottom of the fuel pump. Disconnected it and it runs fine now. Even the local JD service tech had zero idea what the hell the relay and diode are for.

 

[SkidTracks]

Diodes are often used on relays, across their D.C. coils to prevent a reverse voltage spike when power to relay is suddenly cut off. Collapsing Field of coil can fry electronic parts (transistor or I.C.) driving (controlling) relay.

Glad you got it traced down!