Blinker TIP: if the blinkers are blinking fast, usually means a
 

bad bulb in another light.
If you notice blinkers are not properly functioning, check the opposite bulbs for burnouts or weak connections.
ie. front left seem to blink fast, check rear left for bad bulb.
Also the wrong bulbs will cause problems, even if the fit in there ok.

A poor ground will also cause the fast-blink phenomenon. I'm not sure whether the blinker, tail and brake lights all share the same ground in Porsches but in many cars the dimming of a tail light when the brake pedal is depressed is a sure sign that a ground is not conducting.

mine blinked fast, and then the shop replaced the rear bulb and that did the trick.
Although in my hurry to reassemble my car I put the wrong bulb in the front parking lamp and the whole thing went weird. hazards only flashed on one side, blinker did not blink it just stayed lit etc.../ DUH!!!!

That's pretty much standard for all cars. I had a fast blink in my 944 even though both blinkers worked. I cleaned the sockets and that fixed it.
-Chris

I had fast blinkers too and it turned out to be the blinker relay inside the dash.

I'm with cantdrv55...had weird intermitent blinking for quite awhile... tried bulbs, cleaning grounds, etc. etc...turned out to be the flasher relay.