i have a 1981 mustang (fox body) hatch. i added the rear spoiler from a 1989 lx, which has a third brake light in it. my problem is i tried to wire up the light, with no success. my tailight sockets have 3 wires, 1brown, 1green with stripe, and a black wire. i know the black is ground, the green is brake & signals, and the brown is parking lights. when i connect the 3rd. brake light to the green, which is the one for the brake lights, it works when i step on the brake, but when i put my left turn signal on the 3rd brake light blinks to. i know it only does it when the left signal is on, because thats where i connected it to. my car never came with a 3rd brake from the factory. so how do i get it to work properly? do the later ones have some sort of relay or something im missing. thanks in advance for the help.