You are seeing the very same thing that happened last October to my 89 GL 1500. My bike showed the same symptoms as you have described.
I replaced the alternator and the battery and I've not had a problem since. I did replace the OEM alternator with a high output alternator because of the extra lights that are on the motorcycle. Wish you the best and getting yours fixed
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Last edited by AZgl1800; 06-18-2018 at 12:43 PM.