Topic: ‘75 CB360 tail light woes

[minimo]

I’m stumped. Got a 1975 CB360 that keeps blowing the running light on a dual filament bulb at the tail light. Metered the battery at idle = 12.45V
Rev’d the engine to around 4500rpm and battery got up to 13.75V.
Metered the brown wire at tail light (there’s a makeshift ground attached to the fixture that connects to a nearby frame ground) and it fluctuates from 5V to 6V...

I’ve gone through a good few bulbs now trying to troubleshoot this issue but can’t seem to hit on a solution. I checked the connections of the wires both at the brown rear and at the headlight - all seems clean and intact. Also checked brown at ignition and eveything looks very clean there... anywhere else that I’m missing?

Help! Calj737! U out there, buddy?

[minimo]

Forgot to mention that the actual BRAKE light still works fine - that part of the filament has always maintained. It’s the RUNNING light portion that keeps blowing out.
Running a fresh brown line from the headlight bucket all the way to the rear still blows out the running light portion of the bulb.

Metering the brown to ground, should I be getting a steady 12V? I’m getting a fluctuation between 5 - 7V; this was testing at brown from both tail light and headlight connections.

Help.

[minimo]

I guess it would also be important to note that the brake light socket is two wires coming from the socket. I grounded what is essentially the metal plate of the brake light fixture to the bike frame (a connection shared by one of the rear turn signals).

The rear turn signals are LED and I have the appropriate LED turn signal relay installed. Just thought that might be worth to note.

Does this sound like a ground issue with the running light that keeps blowing? Is it related to anything at the front-end of the bike, perhaps at the left/right controls of the bike?

[CycleRanger]

You should check over at the Twins forum and see if those folks have any advice.

http://www.hondatwins.net/

[minimo]

Thanks, CycleRanger. I realize I’m in the wrong forum (my experience has mainly been inline 4 and the forums here) but figured I’d ask anyway :-)


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[CycleRanger]

Thanks, CycleRanger. I realize I’m in the wrong forum (my experience has mainly been inline 4 and the forums here) but figured I’d ask anyway :-)

Nothing wrong about asking here. A lot us have Twins too.
It's just the folks over there might respond a bit faster.

[minimo]

Copy that. Thanks, CR!


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[minimo]

So if anyone is familiar with this short ground connection at the handlebar...

I forgot to install this after a recent handlebar rebuild. Is this what grounds the right handle headlight ON switch, the switch that also turns on the running lights, to properly ground?


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[CycleRanger]

That is meant to ground the bars to the forks due to the rubber isolators for the bars.
You should install it. 

[minimo]

Gotcha. So do you think that by not having this short length ground connected would contribute to the tail running light to blow?

[CycleRanger]

Gotcha. So do you think that by not having this short length ground connected would contribute to the tail running light to blow?

It could be your whole problem. Even it's not it needs to be installed.

[minimo]

Handlebar ground connected from front brake/master cylinder clamp to top triple/fork clamp bolt. Made sure surfaces are bare/clean.
Plugging in a new dual-filament bulb and see how this goes.


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[minimo]

New finding - had to sacrifice another bulb to uncover this:

With the handlebar ground installed, new dual-filament bulb installed, started the bike up with headlight switch in the OFF position and found that when revving the bike up to about 4500rpm, the bulb naturally lit up brighter and Brown to ground read up to about 7V until finally the running light filament burned out.

It’s probably some simple solution that I’m failing to read or consider here...


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[CycleRanger]

New finding - had to sacrifice another bulb to uncover this:

With the handlebar ground installed, new dual-filament bulb installed, started the bike up with headlight switch in the OFF position and found that when revving the bike up to about 4500rpm, the bulb naturally lit up brighter and Brown to ground read up to about 7V until finally the running light filament burned out.

It’s probably some simple solution that I’m failing to read or consider here...

It looks like you've removed the original fork ears and made other changes to the front end?
Somewhere you're missing a ground or have a short.
Real helpful, I know.  sorry.

[minimo]

You are correct, I have changed up the headlight area (headlight bucket and ears are aftermarket)... but would that have any relation to these issues? Hmmm.

I’ve gone through the bucket to make sure the connections there are all alright and they are.

What is causing the Brown to rise in voltage when the headlight is OFF? I know that Brown is connected to the ignition switch but there too appears to be all clean and connected...


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[SF]

Did you have this issue when the front was stock? Try going backwards


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[minimo]

Thanks. The bike was not purchased stock - it came with a lot of aftermarket parts... but, the tail light running light was working the way it should; no issues. I’m going to retrace my steps in the headlight bucket and unplug and systematically Re plug all corresponding wires and will check again.


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[minimo]

Issue solved!
‘75 CB360 tail running light woes

https://r.tapatalk.com/shareLink?share_fid=83063&share_tid=96497&url=http%3A%2F%2Fwww%2Ehondatwins%2Enet%2Fforums%2Fshowthread%2Ephp%3Ft%3D96497&share_type=thttps://r.tapatalk.com/shareLink?share_fid=83063&share_tid=96497&url=http%3A%2F%2Fwww%2Ehondatwins%2Enet%2Fforums%2Fshowthread%2Ephp%3Ft%3D96497&share_type=t

I had the WHITE/YELLOW and WHITE wires switched. Made the correction and we’re back to normal. Thank you very much!


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