Melted small wire from battery NEG to alternator

[Dmace]

So I go to start my CK20HST the other day and turn the key as normal, wait for the glow plug light to go out but then I see some smoke come from under the hood. This was before I even cranked the engine, so I turned the key off and opened the hood to find a small black wire and connector from the Negative battery terminal running in conduit to the alternator. The plastic connector melted causing the smoke. The wire is 10-12 gauge and I am assuming it's just a direct ground from the alternator to the battery but why so small?

Anyone know the purpose of this wire and if the connector is really needed? I have plenty of brand new 10 gauge wire so I'm thinking about just running a new wire from the battery to the alternator and calling it a day. The tractor still starts and runs with this wire melted but I don't want to use it until I replace it.

 

[Coyote machine]

So I go to start my CK20HST the other day and turn the key as normal, wait for the glow plug light to go out but then I see some smoke come from under the hood. This was before I even cranked the engine, so I turned the key off and opened the hood to find a small black wire and connector from the Negative battery terminal running in conduit to the alternator. The plastic connector melted causing the smoke. The wire is 10-12 gauge and I am assuming it's just a direct ground from the alternator to the battery but why so small?

Anyone know the purpose of this wire and if the connector is really needed? I have plenty of brand new 10 gauge wire so I'm thinking about just running a new wire from the battery to the alternator and calling it a day. The tractor still starts and runs with this wire melted but I don't want to use it until I replace it.

Is the wire attached to the alternator or voltage regulator of the alternator?
I think it may be an exciter circuit that gives feedback to the alt/volt reg. This is MWAG. It wouldn't be there for no reason. What voltage are you reading from the alternator at the battery with no load on the system?
You should not have more than 14.25 volts. If you've got 14.9volts or more then the voltage regulator is not working to limit voltage and needs to be replaced.

 

[Dmace]

Thanks for the info, I'll have to take a better look to see exactly where it connects to the alternator and check the voltage when I am near the tractor again. I know it's not there for no reason, my question was is the connector needed? It melted so when I replace the wire, do I really need another connector spliced into the wire or is there a problem with just running a solid wire.

 

[Coyote machine]

Thanks for the info, I'll have to take a better look to see exactly where it connects to the alternator and check the voltage when I am near the tractor again. I know it's not there for no reason, my question was is the connector needed? It melted so when I replace the wire, do I really need another connector spliced into the wire or is there a problem with just running a solid wire.

You're welcome. I was just saying, (to avoid confusion), not to do away with the wire just because it's burned and may look unnecessary. I suspect the connector is there to allow for removal of the alternator without cutting the wire. If the wire runs from point a to point b in a straight line then by all means replace it with solid. It may also allow for disconnection of one end to allow to hookup a meter for testing....

 

[RickB]

If the wire is connected to the negative battery terminal, it is a secure ground for the alternator, not an exitation wire or other signal wire.

If this small gauge secondary ground burnt to a crisp while the glowplugs were activated, the main battery ground cable OR ONE OF ITS TERMINAL CONNCTIONS is faulty.

 

[PoorMansCat]

If the wire is connected to the negative battery terminal, it is a secure ground for the alternator, not an exitation wire or other signal wire.

If this small gauge secondary ground burnt to a crisp while the glowplugs were activated, the main battery ground cable OR ONE OF ITS TERMINAL CONNCTIONS is faulty.

yep... what he said!!

 

[Dmace]

If the wire is connected to the negative battery terminal, it is a secure ground for the alternator, not an exitation wire or other signal wire.

If this small gauge secondary ground burnt to a crisp while the glowplugs were activated, the main battery ground cable OR ONE OF ITS TERMINAL CONNCTIONS is faulty.

It definitely went from the NEG battery terminal to the alternator. I suspected it was just a good clean ground for the alternator but it's pretty small gauge wire. I know I occasionally need to clean where the ground bolts to the frame since it gets rusty so maybe that led to the problem... :confused3:

Thanks again to all!

 

[BobRip]

It definitely went from the NEG battery terminal to the alternator. I suspected it was just a good clean ground for the alternator but it's pretty small gauge wire. I know I occasionally need to clean where the ground bolts to the frame since it gets rusty so maybe that led to the problem... :confused3:

Thanks again to all!

If it connects the negative of the battery to the case of the alternator, my guess is the main ground of the alternator or battery is broken or damaged. Make sure the bolts on the alternator are tight and clean and the main battery ground is good. Basically this small wire carried all of the ground current which can be several hundred amps. It is way too small. Disclaimer: I am not an expert on your tractor.

Edit Was this wire factory or added by an owner? It sounds like it was added to compensate for a poor ground.

 

[northcreek2624]

Derek, I suspect that the problem is not with the little neg wire but,with the big neg wire.
I'm thinking that the big wire has a high resistance(bad) connection at one end or the other,so when you are starting the tractor and using lots of amps the little wire is being forced to carry the load,which it is not sized to do...Mike.
ps sorry for the redundantcy if this was already mentioned by other members.

 

[Dmace]

All this makes sense that the actual ground was not connecting good so it grounded through the little wire but if the ground was that bad then why does it still start fine now that the little wire is melted and not connected?

Also, the wire definitely is factory. I have seen it on other tractors and even brand new 2012 CK20's at the local fair.