1981 GS850L headlight problem..

[amadeusroy]

Hello all. I found you guys out of necessity. I looked around some and this is a very pleasant community, and I hope that someone can help me out.

Recently purchased an '81 GS850, put a few hundred miles on it in a couple days and then all of a sudden the headlight stops working. The only thing that could have caused this other than a random failure is that I washed the bike the day before, and I rode it through the rain.
Naturally I replaced the bulb and that didn't fix it. So I proceeded to check the wiring in the headlight fixture, everything is connected. Checked the fuse box, no problems (switched fuses between similar amp fuses to check). All of the other electrical components except for the tachometer work (tach didn't work when I purchased, wasn't a big deal to me) and the directionals, breaks, everything work just fine. The bike is mechanically very sound and I do not see any break in wiring except for what I haven't gotten to yet under the fuel tank, but looking at it from the side it is all covered in plastic wrap and cannot imagine the problem is in there.

It is very unfortunate for the one light that I really can not ride without (other than breaks) goes out on me. I live up in michigan and we have been having some unusually warm days and I am so sad when I know i have to be home by 3 or else cars will not be able to see me, and it is also a bit nervewracking riding without headlights during the day.

If you might know of anything else I could check, please let me know. Thank you so much for your help.

Best,
Ken

[Redman]

Ken, Welcome to The GSR.

The head light (hi and lo) and the t/signal control unit is the only thing on the "head" (1st) fuse. And you say the directionals work...
And you didnt specifiaccly say that both the hi and the low beam quit, but I gather that is what you are saying....
So not a problem at the fuse, and not a problem between the hi/low switch to the headlight...
so sounds like a wiring problem out in the wiring harness some where on its way to the headlight hi/low switch ... OR a problem with wiring at the Hi/Low switch ... or problem with the hi/low switch itself (I doubt it)... OR... a problem with the ground for the headlight (top on my list of suspects).

I noticed that in your description you did not make any comments to make me think you have a volt-ohm meter. But that would be a good way to further troubleshoot this. And if you dont want to get a meter just for this,...ah, you might be likley to have need of a meter for other problems that could possibly occure, sometime, ah, maybe problem with charging system, just as a random example (a-hem).

Send me your email in a PM (UserCP, Send Private Message, Redman) and I can email you a schematic if you dont have one (I'll be back later this evening.). Or after MR BassCliff sends you a link to his BikeCliff web site, there are links there for manauls and schematics.

BUt for now:
Org/Red is from Head fuse (*)
Org/Red is jumpered (used to be on/off switch) over to Yel/Wht at a connector. (*)
Yel/wht goes to hi/low switch (*)
Yel to hi beam (**)
Wht to low beam(**)
Blk/Wht is to ground.

* should have power when ignitn switch on.

** should have power with ign switch on and hi/low in that position. Measure from the wire/connector to the THAT blk/wht ground wire there at headlight connector. And also from the wire/connector to the bike frame ground. Maybe that blk/wht ground wire isnt really grounded.

Tach is entirely mechanical, driven by mechanical cable. Only reason the tach itself has any wires is for the lights in it.

Tell us more what you find. Plenty of folks here willing to help. Lets get it fixed for any remaining nice enough days that there might be.

Where in general in Michigan are you?

.

[tkent02]

Not sure why it would fail, but a multimeter will quickly tell you.
Check the switch and check any connections along the way.
Somewhere there will be 12v, and somewhere else there won't be.

You do have the proper wiring diagram?

[Steve]

Use a meter or a test light to do your checking. Fuses can look good, but fail under the cap, where you can't see it. Even if the fuse looks and tests good, I doesn't mean much if there is no power getting to it to go through it. By using a meter or a test light, you can follow the current path to see where you lose it. Also, you can have good wires, good connections, good fuse, good headlight bulb, but if you don't have a good ground, you won't have any lights.

If you don't already have a service manual with a wiring diagram, you can download one from BassCliff's site. He will be along shortly with his little welcome thing, so pay attention. LOTS of good information there.

.

[Redman]

Ken,

I made a quick sketch of the just the headlight portion of the schematic. Is a scribble scratch hand sketch (should do in CAD, but that is too much like work). Have added notes about how/where to find the connectors in the headlight shell (I assume).

Look for all these connectors, can identify the connectors based on which wires (by colors) are connected to them and/or where some of the cables go to. Look for all these wires. Unplug headlight. Maybe pull signal fuse and ignition fuse if concered about draining battery (main & head fuse still in though). Ignition switch ON. Then use meter to follow along the circuit to see where loose power. Put meter negitive to any ground wire (blk/wht) you can find, someplace that you can put it and leave it there, maybe can stick meter lead under the rubber boot of a bullet connector and the rubber boot will hold it there, or maybe stick it into a multi connector (square, rectangular) and it will stay there. And then probe with other meter lead to the various connectors/wires to see if power there (and do try both sides of the connector), maybe start at fuse then move along the circuit on connector at a time. Oh, first try to battery plus or fuse hot side to first verify meter set up proper and have good connection on the negitive lead. Go along one connector/device at a time - org/red(3-4 places) - yel/wht(3 places) - yel and/or wht (3 places), If you get all the way to the headlight connector (or maybe start at the headlight connector) and it seems like have power there on the Yel and/or Wht wire (based on hi/lo switch position), then think about where you have the meter negitive lead. Move it to that blk/wht right on the headlight connector and then various other places along the blk/wht wire, but now you are looking for where you regain the voltage reading. Since you say the t/signal work, it seems that blk/wht is a good graound there somewhere or else the t/signal light would not work.

Hum, ah... there is another suspect.
That single connector there on the org/red jumper to the yel/wht wire.


Ew, maybe I should redraw for neatness. Naw, I am not that fussy. Have had too much coffee anyway.

Tell us more what you find.

.

[rustybronco]

Hello all. I found you guys out of necessity. I looked around some and this is a very pleasant community, and I hope that someone can help me out.

I live up in michigan and we have been having some unusually warm days and I am so sad when I know i have to be home by 3 or else cars will not be able to see me, and it is also a bit nervewracking riding without headlights during the day.


Ken

Ken, where up in Michigan might that be?

[brs127s]

Check your ground wire using a test light. On my 83 850GL, the headlight stopped working. It had power all the way to the bulb. I began checking the ground. I had a ground up to the connection under the tank, to the base of the triple tree, but then no ground after that. I found the wire had separated right under the triple tree. I pulled the ground wire from the headlight bucket, unwrapped the harness to the break, soldered the wire back together, rewrapped the harness, and put the ground wire back in the headlight bucket. Never had a problem after that.