I think the rear turn signal lamps do not have running lights. Only the front signal lamps do, unless it's an upgrade..
The running light is in the taillight/brake lamp (+license plate light)
The light bulbs for the front and rear turn signal lamps are different, the front bulbs are a two filament type but the rears are single filament bulbs:
Rear: BA15S base for rear turn signal [1156 bulb],
BAY15D base for tail/brake [1157/2397 bulb]
Front: BAY15D base for front turn signal [1157/2397 bulb]
were both front and back left blinkers fast simultaneously? Usually either the front or back turn signal bulb is not working when you get a fast blinking...
If you re-experience fast blinking, after light bulb and fuse checks, inspect the sockets. It's a sliding contact plate with a spring underneath that pushes the contacts against the bulb's base. that sliding mechanism can get stuck because of whatever reasons. clean the sockets and apply small amount of dielectric grease pushing in the contact plate... make sure you can push it in without much pressure.. watch for the offset pins on the light bulbs.
there are a few discussions about the lights, this is on of them: https://www.vulcanforums.com/forums/...-signal-3.html