How to: Stop your windows randomly dropping / not dropping

[topradio]

Not many months after getting my 986 I found that when I drove over a bump the windows would drop as if I was about to open the roof. The problem was a tolerance issue with the latch switch in the top screen rail. I effected a fix by packing the switch contact plate so that when closed the latch arm pushed the mechanism further up operating the 2 micro switches.

Fast forward 15 years and this weekend I found that the problem had reappeared only now I had to push the switch plate so far that it would have required about 10mm of packing to fix it.

So I removed the assembly and this is what I found



The switch assembly is held by the two spring clips in red. These can be prized off to release the assembly and the clips can be reused if you are careful. The switches, marked in blue are operated by cams on the rotating shaft marked in green.

One of the switches is normally open and the other normally closed and I found that the clearance between the cam and the switch on the right was too great and the shaft was having to turn a long way before the switch operated.

My first solution was to de-solder the microswitch and move it further out closing up the gap to the cam. This pic shows the switch operating lug in red and the point where the switch moves to reduce the tolerance in blue.



Having done this I found that while it worked fine it wasn't very satisfactory as it didn't address the original cause of the problem which was too much play in the operating arm. I found that the arm and its return spring could move backwards opening the gap to the switch (only 1 switch is affected as the other is operated in a different plane). All I did was to insert part of a cable tie between the spring and the body of the assembly and the play was removed. The cable tie is quite a tight fit and won't easily move or fall out and while this seems like a bit of a fudge the alternative would be to buy a new assembly which as far as I can see will likely suffer the same design fault.