Blinker switch defective. This is not always the case. You could have one of many problems. Flasher bad, bad bulb, bad connections.....please check these before you go and replace a blinker switch.
turn signal relay fuse
Replace the flasher relay.
Change the front turn signal light bulb. It's bad.
The emergency flashers and the signal lights are separate systems. Each has it's own fuse, switch and flasher relay. If your turn signals light up but don't blink I would blame the signal flasher relay.
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
Check your bulbs and your flasher.
Could be turn signal flasher Check bulbs Could be a problem in steering column
Probably needs a fuse.
This may very well be a problem with your ground connections at that turn signal.
Why would you want the blinker faster. They should blink at factory specs.