Quick flash signals, check the bulbs.
Mine was doing the quick flashing signal thing, and had read about replacing the bulbs. Removed the tail lights, and found 3 out of the four bulbs were 3057, not the specified 4057's. Replaced all four with new 4057's and has never happened again. Make sure some idiot didn't put in 3057's, hehe. And no, I wasn't the one who put them in.

