try replacing the blinker under the dash that little box that makes the blinker sound
turn signal relay fuse
An open ground or a short to ground when the signal is on. Usually a bad bulb.
POSSIBLY A BADGROUND
Check all of your turn signal bulbs. One of them may be burned out.
your rear bulb is blown - replace the bulb The turn signal blinks fast because the bulb is going out. That is also why the others dont blink.
turn signal relay is bad
Buy a "highway" turn signal flasher
Incorrect size bulb installed.
Generally, a change in turn signal blink rate is an indication of a burned out bulb. Depending on the manufacturer's design, some circuits will speed up, and some will slow down, when the current load is reduced.
Check your bulbs and your flasher.
Probably needs a fuse.
This may very well be a problem with your ground connections at that turn signal.