i bought a cheapo shift light on ebay and it didn't come with any instructions. i have 3 wires: red, black, and green. i am assuming red goes to a power source (switched or unswitched?), black is the ground, but i have no idea what to install the green one to. anyone have a shift light that they installed? can you give me a quick explanation before i break my back trying to figure again?

ben

 

green goes to the negative wire on the coil.