Tail/Brakelight blinking...

[Targetman]

My tailight and brakelights started going on and off randomly by themselves. Have looked all over for loose/bad connections, found none. Also I didn't know about the oil light comming on when the tail light goes out on specials. So, I suspected the "light checker unit" that controls this function. Found a used one at the wrecker to no avail. Problem persists.

When I first turn the key on, both filaments go on in the tailights. after about 20 seconds or so, the blinking starts randomly.
If I unplug that light checker unit the blinking stops, the brake lights work properly, but I have no tail lights.

If I activate a brakelight switch during the first 20 or so seconds when both filaments are on after turning the key, they get brighter!? So, using the brakes makes the filaments get brighter, but they are both stuck on. Weird.

So, when a brakelight switch is activated the blinking stops and both filaments come on. When you release the switch, the blinking resumes. I have disconnected both brake switches and no difference, blinking continues. The brake switches both work properly.

Anyone seen this weird-ass sh*t before?
I am going nuts over this one, got almost the whole wire harness untaped looking for bad wires.



P.S.
Found this interesting stash at the wrecker....

[thumperjsa]

first, make sure the bulb is sitting in tight. Two filament bulbs have 2 connectors at the base. If it spun a little, it could be shorting.

The bulb won't turn on unless it is getting 12v to it so look at the electric diagram for the bike and follow the hot wire for the brake light back to the source. You may have a short across the tail light and another 12 v source somewhere along the line.

I doubt it would be agrounding problem because of the flashing. I don't know much about the light checker unit so I can't say if it is something there. I would go for the most obvious before getting to detailed.

[John]

Have you ever seen an 1157 bulb have the brake/turn lamp filament brake at one end, and fall onto the filament for the tail light or vice versa? That can mess up your head a little trying to trouble shoot that one.

[pathfinder]

Fairing

I had about the same thing a few weeks ago, 78E with a Vetter fairing. I had put something in the right side of fairing the day before, then went to check blinkers the next day before a ride. Left blinker fine, right blinker made the tail light flash. Long story short after wiggeling the right blinker wires in the fairing everthing went back to working fine.

[Targetman]

Yes, John I have seen the filament problem like you describe, I wish this was that simple (well it probably IS that simple, but maybe I'm too simple to figure it out yet)>.

The bulb intalled are actually 2057 bulbs. I will replace them with the 1157, but I don't think that will do anything much.

There are three colour wires comming off of the tailight ass.
Yellow, Blue, and Black(ground).
I think from the wiring diag. that the yellow is the brake circuit, and the blue is the tailight only.
The blue wire goes straight to the Light Checker unit, which gets it's power from either the regulator, or the ignition switch?

If I unplug this checker unit, will it effect anything else?

Maybe I can cut and re-wire the blue wire directly to a switched power wire somewhere and by-pass the checker unit thing altogether? That should work shouldn't it?

Thanks for the replies, btw.

[xs650mike]

You're on the right track. First install a new bulb. Check that the contacts in the bulb holder are bright and not corroded. Next check the ground. That should do it since you've already checked the connections. If you've still got a problem then maybe you have a cracked wire or other invisible fault. Since the light blinks it's an intermittent which complicates trouble shooting but you do have to check continuity armed with the wiring diagram. It would help if you had an ohm meter and a test light. Betcha you find it without these though, in most cases it'll be something fairly obvious.

[Targetman]

Thanks, Mike.
I am going to do the continuity check like you say, tomorrow.
I have the bike parked at my uncles so I have to pick and choose the times that I can ride/work on it this year (I am living in a seedier type neighbourhood this year because we are saving for a house and I don't want to leave the bike in this parkng lot while everyone's at work).
Hopefully changing the bulbs will lessen the dimming effect on all the other lights when I put the brakes on.

By the way, What is the "terminal assembly" in the wiring diagrams? What is its function? Just curious....

[Targetman]

Another thing, you guys have replied about my tailight "bulb" (singular). Does that mean that the 79sf only had one bulb back there? You see my 79 has what is either an 80 or 81 seat, tailight, and fender canibalized onto it. But the TWO bulbs are wired same single power wires, so it wouldn't make a difference i guess...

[xs650mike]

Yep the SF only has a one bulb light. Don't suppose it would matter, but right there is something to check, the PO may not have done such a good job of splicing in the 2 bulb tailight. Your bike sure looks sharp! Wish mine looked that good. I notice the turn sigs are relocated to the licence bracket which I have to do on my XS11SF so I can mount my saddle bags. Already did this on one of my 650s. You might check the wiring on those sigs as well while you're going over the wiring anyway.

[xs650mike]

Or did you do the conversion yourself.

[missinglink]

Check the ground circuit real good. I had some weird (wired) problems and found that the ground wire was broken in the harness on the right side. The lights still worked somehow by getting a ground back through some other lights. The lights were dimmer but worked.

A 2057 is just a brighter (more watts) 1157.

[Targetman]

Hallelulla! I can now see the lights.
Bless you Brothers.

All I did was put the proper 1157 bulbs in, and now they work properly.
What is THAT all about?
Could it be that the "light checker unit" or some other electrical doo-hickey on the bike (or even a marginal connection) was overloading from the extra amp draw of the brighter lights?
I'm going to check all the other bulbs on the bike aswell, just to make sure they're all the proper ones. Then I can charge the battery which is now low on power from all the key-on testing I've been doing (for nothing), and test it out.
Thanks for all the posts....

[Targetman]

Yes Mike, my uncle and I did the conversion of the tail blinkers.
The soft bags fit on so I can go camping AND carry the woman along too. He also gave me some steel wire things he had on his Honda A.C.E to keep the bags away from the suspension and such. Works great.

The bike looks better in the pic than it does up close. I haven't been cleaning it lately.

[Dragonrider]

Sometimes the little led "tits" get worn on the bulbs from vibration...and make intermittent contact even though the bulb is good...maybe that did it?

[xs650mike]

The bike looks better in the pic than it does up close...

They all do but the pic is what the bike looks like from 20 ft. away which is all most people will ever see!