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Discussion Starter · #1 · (Edited)
I’ve gone through a good amount of dual-filament tail light bulbs and trying to troubleshoot why the running light portion of my bulbs keep burning out (brake light is working fine).

With the engine running at idle, Brown to Ground measures around 5V and fluctuates up to 6.57V at 4500rpm (should this read closer to 12V?). Battery meters to 13.7V does this all check out normal?

I recently uncovered this short ground wire that came off of a recent handlebar replacement:

Could omitting this wire relate to the kind of running light issues I’ve been having? Is this wire what the handlebar relies on to ground to the frame of the bike, which is what I have the tail light grounded to at the rear of the frame, when I turn the headlight switch ON, it burns out the running light portion of the bulb?


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Discussion Starter · #2 ·
Connected the short ground wire at the handlebar thusly:

Installed a fresh dual-filament bulb and started the bike (headlight switch OFF position). Rev’d bike up to about 4500rpm and naturally, the bulb pulsates brighter as the rev gets higher. Meter read up to 7V and then the running light filament burns out.

Noticed too while running the bike in idle, turning the headlight switch ON steadies the running light, regardless of any blips or rise in throttle. However, I have found that it only takes a short ride around for the running light to blow again.

Is there something, some connection that I’m overlooking or failing to consider here that is causing the running light filament to blow?



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So the handlebar is grounded to the triple crown, is the triple crown grounded to the main wire harness? Low voltage is hard on light bulbs (excessive vibration is an issue too). You should have twelve volts or better at the bulb socket if the wiring is ok. Check the voltage at both ends of the tail light fuse and at the terminals on the ignition switch.
 

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Discussion Starter · #6 ·
So the handlebar is grounded to the triple crown, is the triple crown grounded to the main wire harness? Low voltage is hard on light bulbs (excessive vibration is an issue too). You should have twelve volts or better at the bulb socket if the wiring is ok. Check the voltage at both ends of the tail light fuse and at the terminals on the ignition switch.
I?m still not clear on where that short ground wire connects (from handlebar to the top triple). Where I have it connected now is not only aesthetically unpleasant but I?m not sure if it?s correct. Anyone with photos to reveal where that wire goes? I realize I have these aftermarket clubman bars but I?ll try to make it all adapt...
 

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That wire is supposed to go from the bottom of the one of the handle bar clamp risers (under the top fork clamp) to that bolt you have it connected to now. Be gentle when tightening those outside fork pinch clamps as too much will crack them. I've modified that jumper on my bikes to be a bit longer and have a male bullet end, ring end goes on the bottom of the riser bolt and the bullet end goes in a spare ground (green) in the headlight bucket.

Now, since you think everything was working before you changed the bars then I would HIGHLY suggest you check ALL the wire connections in the headlight bucket and under the tank. There are some colors that are VERY close to each other that are NOT meant to go together, like the WHITE for the headlight and the WHITE/YELLOW for the charging circuit. I'm saying that because it sounds like you have the White/Yellow plugged into the lighting circuit which will cause the lights to pulse or glow brighter/dimmer as you rev the bike.
 

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Discussion Starter · #8 ·
Frogman79, I bow to you. First of all, you were right...

Though difficult to see in this bad pic I had the WHITE/YELLOW connected to WHITE and vice versa under the fuel tank :-/ Honda also made the connection easy to read by making the connector yellow and I completely overlooked it. Nevertheless, the wire colors have been corrected and now I believe that the tail light is working as it should - the tail running light comes on only when the headlight switch is ON. And there’s no more weirdness with the running light pulsing with the throttle! Thanks so much for showing me the light, Frogman!

I also think I connected the handlebar ground wire to your specifications.
On the right-side outside top triple clamp...

...connected to the bottom of the handlebar clamp riser nut (sandwiched between washer and nut:


So far so good, I think.


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