Blowing Fuse After Wiring Taillight

[szts]

My 81 xs650 came without a taillight. I picked up an aftermarket one. The original wiring ran 6 wires to a plug. The taillight only had three. I cut the plug and stripped the wires. I ran the wires red to blue, yellow to black, and black to green. But after that whenever I hit the brakes the fuse would blow. I need help! Last step before its road ready.

 

[Grinder]

Check your new light to make sure which wire is ground. Some of those have odd wire colors.

 

[XSLeo]

On the bike the blue wire is hot to tail light, the yellow is hot to brake light, black is ground.
On your new tail/brake light you have a red, green and black? I might think the red is tail, green is brake, or the green is tail and red is brake. Black is most often ground. Being as you are blowing fuses when you use the brakes indicates you have the yellow from the bike to ground on the new light. It probably has a ground through the mount as well as the black wire.
One easy way to tell is open up the new light and look at which wires go where. The ground wire is the one hooked to the body of the socket. The other two go to the dots that touch the bulb.
Once you figure out which wire is ground hook it to ground. Now with a jumper wire hooked to battery positive , touch the other two wires, one will light up very much brighter than the other. the bright one is brakes, the dimmer is the tail light.
Leo

 

[szts]

Thank you so much. I will being trying that later tonight. Not sure why it didn't occur to me to open it up in the light. I guess it made too much sense...

 

[szts]

The newest development is that the taillight only shows light when brake is hit. No matter which of the two non ground wires it plugs into. Planning on just running the taillight off the ignition or headlight.

 

[fredintoon]

The newest development is that the taillight only shows light when brake is hit. No matter which of the two non ground wires it plugs into. Planning on just running the taillight off the ignition or headlight.

Hi szts,
that's typically a symptom of a bad ground.
Here's what I'd do:-
Unplug the new rear light and use a multi-meter's lowest Ohms setting to check out which of it's wires do what.
As Leo posted, the bike's wiring should be blue wire is tail light, yellow wire is brake light and black wire is ground. ( beware the dark brown signal wire, it may look black but it ain't)
Wire up accordingly.

 

[XSLeo]

Is the blue wire getting voltage with the key on? If not trace it back to find where it gets lost, it may be your key switch, dirty contacts. It can be take apart and cleaned. Bright and shiny is a good thing.
Leo