Might start with this: http://www.goldwingfacts.com/forums...orum/384168-gl1500-common-ground-gremlin.html
If that does not work, then you could approach the Search further by unplugging all circuits except the ignition... run the bike, then start plugging in one fuse or relay at a time, until the problem appears, at which point you'll have an idea of what circuit it's in. Similarly, you can unplug the entire rear end of the bike (via big connector by left shock, upper end) to largely isolate any ground problem between the rear & front halves of the bike.
If that does not work, then you could approach the Search further by unplugging all circuits except the ignition... run the bike, then start plugging in one fuse or relay at a time, until the problem appears, at which point you'll have an idea of what circuit it's in. Similarly, you can unplug the entire rear end of the bike (via big connector by left shock, upper end) to largely isolate any ground problem between the rear & front halves of the bike.