Brake light blues again

[Beer van Huet]

Hello folks,
I owe a '99 Std F6C, it has a light on/off switch but I don't think that it makes any difference for this issue.
I wanted to have a red (tape) led on the inner side of my sissybar, connected to the rear brake light. It looks nice and is safer.
I noticed 3 wires coming to the rear brake light ; I looked them up in the wiring diagram and it looked pretty simple, green=ground, brown= lights and green/yellow=brake. So I installed the LED and connected the leads to green and green/yellow with the brake light also installed. LED no go.  Disconnected the LED and the bulb operated as advertised again. So I measured the voltage of the leads and noticed that brown had 12V (with the light switch OUT) and green/yellow 0V. This time I connected the LED to brown AND green/yellow and green. No way. Jose
Then I grounded the LED to the frame and green/yellow. Bingo....the brake light and LED worked when I pressed the brake.
When I put my light switch ON however, the bulb went OUT and the LED went ON and neither the brake light nor the LED worked.
I went to the search function of this board and looked for brake light and LED. Lots of stuff about the Radiantz LED and blinking lights but not anything of interest for me in this case.
Now I am getting a little confused. I am merely extending the rear brake light wires to the LED without any luck.
I think Honda has a different electrical brake light system for its' Valkyrie. There was mention about this in the previous discussions too.
So, the system works fine with the bulb only. With bulb and LED and light switch OFF, the system is fine as well (both light up when depressing the brake)
With the light switch ON, (bulb in or out) only the LED lights up all the time.
What am I doing wrong here?

Regards,

Beer#7609

[olddog1946]

I don't have a wiring diagram for your bike, but the significant deal here is L E D (light emitting DIODE).
Diode's only allow current flow in one direct.  You might try switching your leads around in the situation where the LED works and the rest don't, Might work then, or use a mini bulb instead of LED.

[John U.]

Here is a link to one of Chet's (Rattlebars) schematics. Many thanks to Chet for making these available...still.
http://www.rattlebars.com/valkfaq/schematics/rpage03.html

[old grouch]

Not an electrical guru, but just a thought.  This light switch you mention....what light(s) does it turn on/off?  Is it possible that it is wired into the GROUND wire of the brake light circuit?  If I followed what you said correctly, that could account for the LED working when grounded to the frame.  Stan

[Beer van Huet]

Found the problem. It turned out my rear light (green -) wire was not properly grounded somewhere further down the road. I grounded the green wire separately to the frame as well and now everything is working OK. Even better, the light is shining much brighter than it used to do. Since it was working and I did not notice the light to be less bright, it got me.
Connecting the LED was a piece of cake now.
Thanks everyone, for your constructive advice!

[olddog1946]

Glad it's working...