Simple but aggravating electrical problem

[Vansnxtweek]

Hey guys,

So I am in the final portion of my XS build. The bike is complete, painted, registered, and ready to roll. I'm just trying to finish off these last little issues. I'm hoping someone can help me here.

My issue is that I'm having a hard time keeping my taillight lit. It will light up when I start the bike but usually within a few seconds the light goes out. It doesn't blow the bulb, but it wont come back on until I shut it off, move it around a bit and then fire it up again. I have the typical Model A style taillight mounted to the license plate bracket type mount, bolted down with my rear axle.

My obvious thought here would be that it has a shotty ground connection but I shaved all the paint off from everywhere, even tried tying a wire from the ground bolt to the bulb. I'm kind of dumbfounded.

I have a PMA with no battery, using a capacitor. I am getting 14~ volts to the taillight at idle and it drops down some as I rev it. 14 seems a bit high to me, but like I said, its not blowing the bulbs, it just seems like a crap connection.

Has anyone else had any issues with these taillights?

Thanks, and sorry for the ramble, just trying to include all the info. I'm freaking ready to ride!

 

[gggGary]

try ground wire all the way to the charging system ground, the swing arm would be a very poor ground through grease and bearing surfaces
Edit; looked at pic no swing arm LOL, would still bring a ground wire forward to PMA negative connection see if that's it.
Expect a regular bulb to break filaments frequently, good spot for an LED bulb.

 

[fredintoon]

Hi Van,
what Gary sez.
I'd go further, full rubber mount that tail light so it don't get shaken into pieces.
This will completely insulate the tail light from the frame if it's done right.
Then run THREE wires (tail, brake & ground) from the tail light bulb and body all the way back to the appropriate electrical connections.

 

[Vansnxtweek]

Thanks for the help guys. I do have the 12v wires for the running light and brake light run through the frame back to the connections. I'm not sure how to run a ground wire being that the housing grounds itself. I guess I could tie a wire from the mounting bolt of the housing back to the box? Not sure how I'll run that through the frame. I do agree completely that my issue is most likely because of the paint/grease and such. I should have thought of that when I initially installed everything. Doh.

Fred, I agree with the rubber isolation..this thing is a shaking machine for sure!

I was thinking LED as well, Gary. Thanks for your test tip!

 

[fredintoon]

Thanks for the help guys. I do have the 12v wires for the running light and brake light run through the frame back to the connections. I'm not sure how to run a ground wire being that the housing grounds itself. I guess I could tie a wire from the mounting bolt of the housing back to the box? Not sure how I'll run that through the frame. I do agree completely that my issue is most likely because of the paint/grease and such. I should have thought of that when I initially installed everything. Doh.

Fred, I agree with the rubber isolation..this thing is a shaking machine for sure!

I was thinking LED as well, Gary. Thanks for your test tip!

Hi Van,
grounding through the frame is OK when it's new but almost any subsequent contamination can stop it working right.
Yamaha ran all those black grounding wires to each and every electrical component for a good reason.
I'd suggest opening up the tail light and attaching the ground wire to the actual bulb-holder.
Either by soldering it on or by using a small nut, bolt & ring terminal.
Lead the ground wire out through the same grommet as the stop & tail bulb filament wires.
As to fishing the ground wire through the frame, surely there's room for one more if you try?

 

[TwoManyXS1Bs]

I've come across intermittent lighting like that a few times. Found problems in the bayonet socket, like:
- Broken insulator tabs that won't keep the two contacts aligned.
- Screwey/bent spring that won't apply even pressure to the contacts.
- Not enuff slack in the wiring to allow the spring to extend.
- Mysterious lack of continuity in the contacts (fixed by renewing solder tip)
- Lack of continuity at the underside of the hook that engages the bulb's pins.
- Poor connection, loose screw/rivet of the socket housing/tab to ground.

Have you trued wiggling it around after it blinks out, *without* stopping the engine?

 

[weekendrider]

Lack of continuity at the underside of the hook that engages the bulb's pins

Seems to me in an effort to lower costs the pins are shorter now. If the bulb "rocks" in the socket you might try pushing the hook area in so it will grip the pins tighter.