Tail/brake light wiring

[muskies666]

i bought a small led tail light for my 79 gs750 and it has two wires, red and black. The stock light uses three. i have a wiring diagram but it doesn't help me much in this situation. i was wondering if anyone has wired a similar setup into their bikes and how they did it. Or should i just sell the led light and look for a different one.

Thank you

[Dave8338]

In order to make it (the single LED that you have) work...it would need three wires. 1-for the ground 1-for the tail light and 1-for the brake light. I put one in a bike that I'm building but it was a three wire set up.

[lucabond]

Is it in a metal mount ? If so I would think the metal frame is ground, you would just add a wire to it to ground it. If it mounts to metal instead of plastic the mounting screws would be ground or the 3rd wire if it goes to plastic you add the wire to a mounting screw than ground it that way. That would be my guess. This based on your post of brake\tail light.
So figure out which of the 3 wires you have is ground and put that 1 on the mounting screw.

[bonanzadave]

Rusty did it with a truck light.

http://www.thegsresources.com/_forum/showthread.php?t=130447&highlight=led+truck+light

[muskies666]

the led light was part of a chrome plated tag mount that mounts to the swing arm. im not using the tag mount, but the light has a metal back with screws sticking out, ill look inside to see if the led is grounded to the back plate. i guess i was mainly wondering what the three wires were. thanks a bunch ill try and get it lit up.

[Steve]

ill look inside to see if the led is grounded to the back plate. i guess i was mainly wondering what the three wires were.

No need to take anything apart. Just connect the metal back plate to the negative terminal of your battery and connect the red and black wires (one at a time) to the positive terminal to see if you do, in fact, have two levels of illumination. My guess is that you don't. You might just have a marker/tail light, and it is not bright enough to use for a brake light.

.

[muskies666]

you were correct on the marker light and not brake light. the black wire was the ground and the red was on. when i took it apart, i saw they just used a regular tail light, and removed the bulb and ran an led through there. luckily my old wiring and bulb from the stock light fit perfectly. so i now have a working light the size i want, just no leds which i dont really care. i am concerned with the stock bulb being a lot closer to the lens now and melting it. i'm not sure how hot they get, but the light will only be on when im braking or at night (i run my lights off during the day because i switched to a 9 amp hour battery). I will see what happens.

Thanks for all your help.