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I recently bought a '94 R100R with a GS fork as a project bike to achieve my long time GS airhead dream. I have owned a few airheads in the past and am a competent mechanic overall. The R100R was all together and starts and runs. The headlight low beam doesn't come on with the ignition switch and only the high beam flasher works lighting up the bulb (also new LED H4 type) and the indicator light on the instrument panel. The horn button and turn signal buttons also don't seem to work. Horn is functional as a unit.
The Neutral light did work but now doesn't and the turn signal indicators also don't work on the dash lights.
Some bulbs are out like the park light bulb in the headlight and the speedo bulb but I don't think those are part of the issue. Would a faulty bulb open a circuit for another light?
I have the Clymer and Hayes manuals with wiring diagrams and a working voltmeter but electrical issues are my Achilles heal. I also am color blind so that adds an level of complication.

I have gone over the bike part by part to clean it up and look for issues even cleaning connectors one at a time with a wire brush and dyna grease. Everything seems to be working and the bike starts and runs.

Looking for some diagnostic support to try to fix myself in airhead fashion. I am eager to get this bike on the road. Thanks.

The high beam flasher is a separate circuit from the usual headlight circuit. It runs on a separate hot (usually a red wire) than the headlight relay. You're missing power there somewhere. Possible the headlight relay is fritzed or there's no power to it. Start there, and worry about the little things later.

Yes, replace any bulbs that are out.

Have you checked the fuses?
Circuit tracing on these bikes is much simpler with a test light than with a voltmeter. Minor voltage discrepancies are not an immediate concern in this case; you just need to see where there's power and where there isn't.
When you run across simultaneous over-lapping problems that don't make sense, it always a ground circuit issue.

btw - Do black & white wiring diagrams help when you're color-blind?

I had this same problem, IRARYAN did you figure it our?

iraryan wrote: ↑Mon Jul 19, 2021 10:01 am I recently bought a '94 R100R with a GS fork as a project bike to achieve my long time GS airhead dream. I have owned a few airheads in the past and am a competent mechanic overall. The R100R was all together and starts and runs. The headlight low beam doesn't come on with the ignition switch and only the high beam flasher works lighting up the bulb (also new LED H4 type) and the indicator light on the instrument panel. The horn button and turn signal buttons also don't seem to work. Horn is functional as a unit.
The Neutral light did work but now doesn't and the turn signal indicators also don't work on the dash lights.
Some bulbs are out like the park light bulb in the headlight and the speedo bulb but I don't think those are part of the issue. Would a faulty bulb open a circuit for another light?

I have gone over the bike part by part to clean it up and look for issues even cleaning connectors one at a time with a wire brush and dyna grease. Everything seems to be working and the bike starts and runs.

Looking for some diagnostic support to try to fix myself in airhead fashion. I am eager to get this bike on the road. Thanks.

I have the Clymer and Hayes manuals with wiring diagrams and a working voltmeter but electrical issues are my Achilles heal. I also am color blind so that adds an level of complication.

The fact is that the current light bulbs are old enough to maintain constant operation and I have not used conventional light bulbs for a long time. I use only energy-saving light bulbs or smart light bulbs because I consider them more reliable and convenient to use. If you change the bulbs, then your problem will disappear, although if the problem is not in the bulbs, then a complete diagnosis of the electrical circuit is really needed here. Perhaps because of problems with it, the indicators do not light up and some light bulbs do not work. I hope you will cope with this problem very quickly. Good luck friend!