I don't remember if my 88 shelby z did this or not, but the 85 laser is doing it and driving me crazy. If I have to turn the 4-ways on for some reason and apply the brake at the same time, they don't flash. Why? If I can brake and use a turn signal at the same time, why doesn't this work? It seems like it should. I don't have a wiring diagram handy in front of me, but do they (for some strange reason) use the same filament in the bulbs?
What gives, and how can I change it so it works with the brake applied?