My charging system on my 4240 is not working right. Amp meter shows overcharge and then neutral charge then stops working. I have changed the alternator twice and still having the same problem..I ran the batteries dead. I hooked a wire straight from the alternator to one of the batteries and the system worked for awhile at least kept the AC working. It acts like a wire is broken. This morning though the system charged for awhile and quit. Is there a regulator or something in the system that quits working after a short time? I really know very little about electric
 
There was problems with the small wire coming from the cab to the two wire plug of the alternator. Deere made a kit to fix the problem. See what the wire looks like and check for 12 volts. I am thinking it was a resistor wire.
 
Sometimes the wire is broke on the curve in the wire close to the alternator.What mathies wrote fixed neghbors same problem.
 
(quoted from post at 20:03:06 06/26/20) There was problems with the small wire coming from the cab to the two wire plug of the alternator. Deere made a kit to fix the problem. See what the wire looks like and check for 12 volts. I am thinking it was a resistor wire.

The original setup was a single strand of resistance (Nichrome) wire, very brittle stuff and it would break inside the insulation causing the alternator not to "excite" and begin to charge.

DEERE's "fix"was a $$$ separate little harness with a diode plugged into it, AR90840 @ some $60.

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You can do the same thing with a $0.50 diode (1N5408 or similar) and a few feet of 16GA wire.

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Note the resistance wire from Terminal 1 on the alternator to "3" in the bulkhead connector, that's the wire that fatigues and breaks.

The complete length, from the terminal in the bulkhead connector to the #1 terminal on the alternator can be replaced with a length of #16 automotive wire with a diode spliced into it.

The end of the diode with the white band is the cathode and goes towards the alternator.

This is the same thing the $$$ DEERE replacement harness does.
 

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