There are three wires on the booster: a wire to input the 6 volts, a wire to output the 12 volts, and a ground wire. I mounted it on the firewall, and inserted it in the wire that leaves the taillight fuse. I now have incredibly bright taillights. Unfortunately, since the brake light/turn signal lights are still 6 volts, you don't even notice when they come on. I may switch it to the brake light fuse wire for now ( I plan on buying another booster for the other lights).
