The drivers window on my 03 996tt has started rolling down by itself. It happens when I turn off the ignition and open the door. The window lowers the 1/2" for the seal like normal but then continues all the way down. I can raise it back up via the switch or with the key in the door. Battery is 100% and I have "re-trained" the window multiple times. Any ideas?

 

The times the windows of my Boxster manifested any misbehavior -- failing to drop when the door was opened or worse droppng as they should but then after the door opening going back up again -- this proved to be a bad door lock controller. A rather large plastic/aluminum housing with some electronic "smarts" and some electro-mechanical hardware inside.

The windows never manifested the behavior of dropping all the way down on their own so i can't say for sure the door lock controller is the problem.

A tech with the Porsche diagnostics computer can query the security controller for any errors and the error code can point to the problem. This assumes the security controller has any error logged. The controller is pretty sophisticated though and something as critical to the proper operation of the system like the door lock controller I think would be likely to produce an error code.

Worth a shot to have this looked into maybe. The controller is a pretty expensive item and one doesn't want to replace it if it is not bad.

I can't forget to mention be sure the the door bottoms are dry. If damp (or wet) the door membrane is bad and allowing water from the wet side of the door to get into the dry side and this will initially cause electrical gremlins at the doors/windows but if left unaddressed will eventually have electrical gremlins appearing at more distant areas of the car's electrical system.

While you are there check the cabin floor is dry. Water from an overflowing body water drain can wreck havoc on the car's security module -- which is located on the cabin floor under the passenger seat (USA cars).

 

No moisture present anywhere around the doors or security module. I am starting to think it is a faulty controller on the window motor unit itself. After reviewing the wiring diagram it shows that the inside and outside door handles switch leads are wired directly to the motor. This is to initiate the 1/2" roll down when the door is opened. Only operating the indoor handle makes the window roll all of the way down. The outdoor handle operates as it should. Looks like ebay is filthy with salvaged window motors. Probably going to pull the door panel and inspect to make sure there is no moisture in the connections but my guess is that I will end up ordering a motor.

 

Haven't check the wiring diagrams but I'm not sure the window motor has the smarts to just drop 1/2" upon door open. That's the door lock controller's job. Thus if the window drops all the way down on door open that would be to me a door lock controller problem.

But I guess you can try a "new" motor. And I can dig out the wiring diagrams...

Added: Well, the motor has more inputs/outputs than I thought it would have. There's door contact, comfort close, to let down, to lift, release FAP [sic] up, term 31, term 30, and comfort open.

I suspect the motor costs way less than the door lock controller/assembly so if one is going to throw parts at the behavior the motor is the less expensive part to throw.

 

Ordered a used motor for $30 and will test it out. Looks like all of the "smarts" are located in the motor. Considering the low mileage on my car I will assume that the window motor I receive will have many more "laps" on it. My hope is that I can just transfer the logic portion of the assembly.

 

For any other newbie Porsche owners out there, when all else fails listen to these guys and disconnect the battery for a half hour. I thought that concept was too simple and spent a few hours with my nose in the wiring diagrams. I now have a replacement window motor on its way to me but everything is working fine because I RELUCTANTLY tried the battery disconnect method.

 

Sorry. I was remiss in not advising you to try the battery disconnect "trick". It is the automotive equivalent of flipping the big red switch on a PC and often at least in the case of a car it doesn't help but in some cases it does. Yours is a case in which it helped.

BTW, this I think explains why at the dealer today when I asked what could possibly be the cause of the symptoms you were reporting the person I spoke to couldn't recall ever seeing this behavior. The reason is I guess wehn the techs spot this behavior (or other seemingly inexplicable window/door lock/etc behavior) after reconnecting a battery they just do the disconnect first.