Published in the January 2015 issue of “Die Porsche Kassette”

Just a quarter of an inch drop in the window is all your convertible needs to allow the door to open without hitting the convertible top’s frame.

In order to water-seal properly, the cabriolets slightly raise the window so that it tucks under the top’s frame after the door closes

But because it is under the frame, when opening it needs to drop the 1/4 inch.  The factory accomplishes this by installing a microswitch on each of the car’s door latches.

As you start to pull on the door latch (interior or exterior) a microswitch closes and sends a signal to the Central Locking System (CLU) telling it to drop the top edge of the corresponding glass by 0.25 inch.  When the door opens, the glass clears the frame and stays lowered until the door is closed again.

But, sometimes they start acting up and the top’s edge of the window catches on the frame as the door is being opened or won’t allow it to close.

Slamming it harder is not the answer as it could cause the window to shatter.

You have to find what’s causing it in order to get it fixed.

In rare occasions the microswitches are damaged or are disconnected when some work has been done in the door panel.  They are easy enough to measure to make sure they are closing the circuit when the door latch is pulled.

There could also be a problem with the electronic part of the door locking mechanism.  This is also a common failure.

But most of the time, probably 9 out of 10, it’ll be the window regulator that’s the culprit.  The way the window regulator works is by a motor which moves the base of the window up or down on two elevator tracks as a braided steel cable winds or unwinds on the motor’s pulley.  It’s very simple but it requires the braided cable to be taught at all times.

Eventually with age and heat, one of the plastic cable guides breaks, allowing the cable a little slack.  When you now pull on the door latch the motor moves the required steps, but the slack in the cable doesn’t move the window at all or just 1/32 or so.  You can test by pushing down on the top edge of the glass.  If the window lowers the required amount, the regulator is damaged and needs to be replaced.

Replacing it is not terribly complicated, but it requires removing the door’s panel with all of its associated hardware which can get tricky because of its clips, screws and connectors, both mechanical and electrical.  In most cases the side-impact airbag will also need to be moved in order to allow enough room to remove the old regulator and install the new one.

Each regulator is specific for a model year and side of the car.  I do not recommend purchasing used because of the likelihood of the aforementioned piece of plastic breaking because of age.

For more information on the window regulators and more, please visit my website: www

Happy Porsche’ing,

Ⓒ2014 Technolab /