John Deere 3010 electrical system?

I replaced the charge indicator light with an entire new assembly and replaced the generator with an alternator. Everything worked as advertised for about three weeks and then the warning light came on while using the tractor and it stays on whenever the switch is on. I've checked that the alternator is working properly with voltage tests at the battery and starter solenoid. The battery stays fully charged and stays up after repeated cold weather starts. The oil warning light works after a bulb replacement and I think these lights are on the same circuit. Any help or suggestions?

Opa
February 2009