Most likely voltage regulator but you should run the wiring system checks as outlined by JD in the order listed in your tractors service manual. Don't throw parts at it as they are very expensive. If you don't have the manual see if your local dealer can copy the part of the manual you need. Roger
Just a heads up if you find that the regulator is faulty and needs replaced. The replacement reg. I got from the JD dealer a couple months ago was made differently than the original. The original bolts were too short to work with the new one.
Went back and they gave me a couple new ones(metric), and problem solved.
Sorry I don't remember the length but they were long enough to go thru the reg. mounting holes plus maybe 1/2".
BTW, working space is very limited for R&R on the regulator.
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