Its probably a bad flasher or sometimes a bad bulb can cause that to happen.
Usually, a fast blinking turn signal means one of the outside turn signals (front, back and side) lights is burned out.
Turn on that fast blinking signal light and check to see if the front and rear signal lights are both working, chances are you have a burned out bulb. If both front and rear bulbs are flashing fast, replace the flasher relay.
A bulb has burnt out that is why it is blinking fast. Check the front and rear bulbs.
If it's blinking, it's a turn signal.
A fast turn signal blinking can be caused by a bulb that is getting ready to out or a bad ground. Remove the bulbs and look for corrosion around the base and in the bulb socket.
Usually when ones turn signal is blinking fast its telling you that a turn signal bulb (and in some cases a brake light bulb) is out. If it blinks fast when you turn on the the left signal the burnt out bulb is on that side of the vehicle (could be front or rear bulb so you'll have to check). And vice versa
sounds like you have a bad turn signal flasher One bulb is bad. The right rear turn signal bulb is burned out
When blinker is blinking too fast it usually means one of your turn signal bulbs are burnt out. Check if bulbs are working. If not replace blown bulb.
A light bulb needs to be replaced. The signal is fast because the electrical current is there, but since it does not turn on the burned out bult, it makes the others work twice as fast.
One of the bulbs is out. Replace it.
The new bulb is already burned out, not seated properly in its socket, or you replaced the wrong one. Get out and look at the signal lights while they are blinking fast. Either the front or rear light is not blinking at all. That is the one that needs to be replaced.
If the right blinker is blinking really fast, it means that there is a turn signal bulb on the right side that is burned out. (coulod be either front or rear)