01'JD 4110 how to check alternator?

[ROUSTABOUT]

why does engine instantly die out when positive cable is removed from battery?

On these newer alternators disconnecting the alt while running is a big no no.

 

[MTGreen]

Positive 12 volts is required to keep the run solenoid in your injection pump energized as has been mentioned. Remove the 12 volts and that solenoid springs closed and cuts the fuel which is the reason the engine shuts off when you turn the key off.
Also despite seeming counterintuitive, the voltage regulator in the newer type alternators requires 12 volt input from the battery at very low amperage for the regulator to operate. When you don't provide this 12 volts the alternator appears to not charge when tested on a voltmeter.
Because of these two things, the engine is not designed to be run with either battery terminal removed or with no battery at all.

 

[2001 JD4110]

Ok I got it, I don’t/won’t pull the battery terminals when running. That being said, I’m still stuck with my charge light/charging system funky. I can pull the alternator & hopefully get it checked but at a JD dealer or a car parts store? Too continue…

 

[2001 JD4110]

Battery charged to 13+v, unplugged alt. Start & run 2k+ rpm check a/c v output= 45v seems good? Reconnect & start, batt light off. I’ve tried cleaning up that alt connector which is burnt up a little & will consider options for renewing at least the spades…? I cleaned up the ground to frame cable yesterday.