<!-- from fixya rte -->Left turn signal flashes very fast - 2010 Dodge Journey SXT

SOURCE: Left turn signal light flashes very fast and does

Have you tested the left rear signal light / brake light to see if the bulb is burnt out. You should also test the socket to see if there's power going it if the bulb is good.

It may also be your electronic flasher module that could be acting up (located near your steering column and will be labeled)

SOURCE: 2004 Dodge Durango: Left turn signal blinks fast

Check the bulb socket for a burnt or a shorted condition. Remove bulb and try another bulb, if it does it again then you have a short in the socket or wiring to bulb. Turn on the 4 way flashers and see what it will do. If it continues then look for any burnt wire connector or wireing to bulb. Check the wiring behind the light for any metal that has cut into the wiring insulation. Hope this will help you.

SOURCE: LEFT TURN SIGNAL FLASHING FAST. i REPLACED BULB

you replaced a bulb are all the turn signals front and back flashing.
If not then you need to replace the other bulb.
If all bulbs flashing fast you need to replace the flasher relay ( under the dash ).

SOURCE: 2005 Dodge Magnum RT. Left turn signal in rear,

When its blinking fast look at both front and rear to verify which bulb isnt flashing. If the right works OK, then the flasher is OK. The flasher is INSIDE the front control module/integrated power module. If you cant find the problem, you may need a dealer to check it.

SOURCE: right turn signal lights flash very fast

check to see if the front or rear bulb is burned out most of the time one bulb burns out causing a faster flash on that side.