I'm assuming you/we are talking about the headlight?
I bought this bike (1983 GL1100a two years ago (after 6 owners that I was able to track) and everything worked great the first season. I saw no reason to switch out the lighting sources on the bike. However, I started having ignition problems on my last couple of rides 2 years ago, so I hooked up my Digital Voltmeter on a ride to see what was going on, and checking the voltage after about 20 miles, I was down to 11.8 Volts. It would not charge above that until I pulled the Headlight Fuse at which point it, jumped back to 13.9 Volts Continued the Daytime ride sans the headlight, but using my LED Running Lights for safety, and never dropped below 13.6 Volts.
I figured if I could get an LED Headlight in, it would solve my charging problems at least temporally. Then the saga started.
I tried about 8 different LED Light options with various outcomes as indicated below. Every light "Bench Tested Good" both before installing in the bike and after failure or disappointment.
The H4 LED Bulbs with the little powered fan on the back worked great, however I didn't want to cut a hole in the headlight socket of the Fairing to make it work.
I then tried 6 different Manufactured Low Profile H4 LED lights of which only 2 worked. When I say worked, both High/Low Beams came on as they should with the switch. The 4 that didn't work, worked fine on the low beam, but went black on the high beam.
Of the 2 that worked; the light output of the 1st. was pitiful at best, and dangerous at worst.
The other one that worked, worked great except for the light pattern between High and low, there was a 6" dark zone at 10'. and seemed to point at the moon at 150'
So, I bought a multi-bulb LED light housing like Harley has these days. Center 5 Lights = Low Beam ..... Top/Bottom 4 Lights each + Center 5 Lights = High Beam. When I flipped the High Beam Switch there appeared to be a direct short on the bike, so I shut it down.
This is when I took a break and started reading up on electric equipment testing, faults, diodes, resistors, etc. Then one day taking a shower, the Light Bulb in my head came on, and that's where the idea of putting the diode in the low beam wire came to life. Once complete, everything worked correctly, all 8 LED Solutions worked, but I decided a headlight housing specifically for the LED's was the best way to go.
Additionally, I permanently wired in a digital LED Volt/Ammeter above the right side glove box, with everything wired through a shunt so I've got an accurate reading on everything the electrical system is doing while riding. Rarely am I now drawing more than 0.8 amps off the battery when running 2 sets of running lights, extra LED's on the rear of the saddle bags, and scoot boot. It will jump to 1.4 amps when I hit the air horn that also activates the flashing brake lights simultaneously. After about 2 minutes the amp draw returns to a range between 0.00 and 0.08. And I never drop below 13.5 volts with everything running.
I'm hoping I can get another season before I have to install the PoorBoy I'm building. Then again, I drive School Bus, schools are shuttered in Oregon at least until the end of this month; most likely until the end of the school year, so who knows?
Alan Miller