Brake Light Wiring Issues

[Pollmann]

Hey guys,
I am having some trouble wiring up a tail light for my 1982 Yamaha XS400 Heritage Special. I bought a new aftermarket brake light and it came with a black wire, a yellow wire and red wire. I "think" it is black=ground, red=brake, yellow=running. Now, the stock tail light has two separate bulbs for each the brake light and the running light. It has two blue wires, a yellow wire, and a black wire. Again, I am guessing it is black=ground, 2x blue=brake, yellow=running.

I attempted to wire it up as follows:
STOCK AFTERMARKET
black------>black
yellow----->yellow
2x blue---->red

This wiring ended up leaving me with a running light, but no brake light when the pedal is pushed. I tried swapping the yellow to a blue and the other yellow to the red but that came out with the same results. I am not very experienced at wiring so I'd really appriciate some help if anyone could shine some light on my troubles. I'm thinking it might have something to do with the double blue wires

Thank you, Eric

 

[S3Rider]

I wired in a Daytona 675 light onto my Speed Triple. My tip to you is to go get a test light. Then test the originals. You may have some issues farther up like a switch gone bad. Either way that is a solid way to find where the problem lies.

 

[Onetype]

Yellow is brake, blue is running light. You only need one of the blue wires not both.

 

[Pollmann]

Great! Thanks guys. I'll try the single blue wire first and if that dosn't work out I'll try getting a test light.