Flasher is bad. to replace it it is under the dash at the back of the steering column.
More then likely it needs to be replaced, if its the actual signal inside the car, turn it on check outside the car which one it is and replace!!
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
Flasher relay.
This happened to me. When my turn signal lights went out or would stay solid where I would have to manually make them blink it eventually made my break lights go out, but they would come on when I held the turn signal switch for high beams. To repair the issue you will need to get the whole turn signal switch fixed which is behind the horn and the airbag. Nice penny and it takes about 2-2 1/2 hours to repair it because there are wires behind your steering wheel that go to different things.
Why would you want the blinker faster. They should blink at factory specs.
Check your bulbs and your flasher.
If the check engine light does not flash when in the diag mode, the problem is the computer. Could be as simple as a failed lamp driver but a failed computer is toast and will need to be replaced/
I would highly suspect that there is a bulb out. Remove the Eight million hand tightened screws and the trunk lense will come out to access the socket. But check to see which one is out first.
Probably needs a fuse.
You either have a bulb burnt out or the turn signal flasher is bad.