Turn signal back feed

[5th_bike]

Take a look at the wiring digram and you will see that the signal indicator bulb uses the "other"'s filament as ground, that explains why the other light flashes along gently.

[alantf]

Ah........I missed that. Our European bikes have a single filament bulb (no marker lights)

[Road_Clam]

One of the things i've learned over the years is that when it comes to electrical gremlins, it's usually one of two things. A corroded ground, or a corroded connector. These can be a PIA to track down. Many times connectors that reside near the battery tend to corrode from the acid vent vapors. Another common point for corrosion is inside the headlight bucket, which the mfg's love to pack a rat's nest of wires. Look for the tell tale "blue powder" near the terminals. This is the enemy. Corrosion causes wires the heat up melt and fuse together causing system backfeeds. Corroded ground connections are famous for causing lights to intermittently dim. I have a learned diciplin of using die-electric silicone grease on all my bikes connectors and grounds.