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.
help with third brake light
- Thread starter retep69
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ID89GT
10 Year Member
Usually the third brake light is wired seperate of the rear lights, that's the whole point of having a third brake light. Say if something were to happen with the wiring for the tail lights, you would still have the functioning brake light for safety.
ID89GT
10 Year Member
Technically that is how you should do it. I would splice it somewhere off the body harness, maybe look at a wiring diagram to see where it is spliced from factory on a newer Mustang that comes with a 3rd brake light from factory and try to copy it as much as possible.
Actually, the whole point of the third brake light is that, starting with the 1986 model year, the NHTSA mandated that every vehicle must have a "center high mount stop lamp", or CHMSL, to decrease the likelyhood of a rear end crash, due to the following driver not seeing the lower brake lights.
Saleen0679
10 Year Member
