1987 gt third brake light on (Page 1/1) T star SEP 10, 11:35 AM I've got 87 gt, third brake light comes on when lights are turned on. With car off depressing brake causes dash back lights to come on and warning dinger to sound, and parking lights to illuminate. Definitely weird feedback short, just haven't found it. Anyone had this? A few years ago there was a post with exactly the same fault.