Check the electric connection at defogger end to check the continuity and then at switch to figure out if its sweitch is faulty or defogger time to say bye bye.
It cud be some tyre may be swollen (manuf defect) shud get free replacement. If not check for some stone or gravel stuck in tread making this constant blop blop upto 80.
Every owner goes thru this once in a while.
Here is my contribution to this Porsche community:
http://perryandcoblog.com/2009/11/17/porsche-carrera-911-996-dead-battery-locked-hood-solution/
Admins: make this sticky.
hi i am a owner of Porsche cayenne 2005 and i just noticed that the alternator is spoiled so i took it to the garage and they said that the water pump that needed changing
he would give me the cost as he said that it will depend on the parts and the labour will see the work and will charge me accordingly. dose anybody knw the estimate