Turn Signal

Ever since I got my 96 jgc back from being repaired. (hit back of trailer-took out front grill and some headlight) my left turn signal has been acting up. It only happens when the lights are on, and whenever I stop, the signal speeds up from normal speed to a faster blink, as if one of the lights are out. Ive checked the lights, and replaced them all (that center mounted brake light is a pain in the a** to change) but the signal is still screwy. What up with that?