Topic: Weird turn signal thing. Suggestions welsome.

[Patrick]

My college boy son has been rising my K5 750 at school for a couple years. He recently brought it home for me to tune and adjust everything (his idea of maintenance is scraping the crud off the windshield every once in a while so he can see) and I ran into a strange problem with the front right blinker.

The left side signals work just fine. When I turn on the right blinker, though, the front blinker and the running light go out. The running light works when the signal is not engaged, but when you engage the signal is not only does not light but the running light also goes out. The left running light continues to work whether the signal is engaged or not. I have verified that there is juice to both lighting elements in the front right light. There is only juice to the signal element when the turn signal is engaged. With the bulb out I get juice on both the turn signal lead and the running light lead when the right signal is engaged. The bulb is good, as verified by switching the bulbs in the front blinkers. The ground must be good because the running light works.

So why won't the turn signal light up or work? Ideas anyone?

Patrick

[Joel]

Have you checked inside the switch housing for any shorts?

The turn signal switches function by passing current to the parking light leads when the switch is in the center.  When it's switched to either side, the parking light on that side is turned off and the lead from the turn signal flasher is passed to the signal lead on that side.

[KeithB]

I know this will sound obvious  but have you replaced the bulb?
This is a dual filament bulb with one for the running light and the other for the flasher.
Swap the one from the other side in and see what happens.
If the problem persists, pop open the headlight shell and check the wiring.
There should be 2 wires to each light so check the connections to be sure there is no corrosion and they are tight.

[HondaMan]

+1 what KeithB said: if on filament is broken and draped across the other post, it will act like you describe.

Rust can do it, too: if the ground is poor, the voltage divides across both filaments instead of one, and the flasher does not work right. Check inside the lens and socket for water damage: there should be a little ground wire to a screw (on most of the '75 Honda lamps) that connects to the housing. The housing is supposed to connect to the forks at the headlight ear. The ear is supposed to be grounded through the headlight shell's mount bolts to finally make it back to the GREEN wire in the headlight. But there are so many junctions along the way that you might call it an "accidental" circuit.

I've seen lots (4) of K4/K5/K6 and "F" bikes (750/550) with the problem you're describing: it's been crusty grounds on all of them. 

[michrobi]

Thanks Mark. You answered my question from another post. The ear to bucket bolt wasn't in and my ground was suffering. Bolted it up and my lights all work normally except the rear right blinker. Took the lens off and it looks like my right rear bulb was effed. I guess the 6 hours I screwed around with my ignition switch wiring order yesterday was barking up the wrong tree. You are the swiss army knife of CB knowledge. Thanks for getting me back on the road (again).

[Patrick]

I found the answer and, as usual, it was my own fault....

It was indeed a ground problem, which I suspected, but I took the light assembly apart and everything looked good. So I pulled the Vetter fairing to check the wiring in the headlight housing. It was fine. Then I remembered that when I remounted the fairing I put a couple strips of neoprene between the fairing and the mount to absorb some vibration. This is a Vindicator fairing. The turn signals ground through the fairing mount. And by putting the neoprene in there I had effectively cut off the ground. Now I can't figure out how the left signal and running lights worked.

The neoprene is out now and the signal flashes like it is supposed to. Now back to the tuneup....

Patrick