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elec window motor not-stopping-at-stop-position issue


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Sorry if this is a previously-answered question, had a look with the search feature but whilst could find threads about resetting the stop positions or replacing the regulator, couldn't find the answer to this.


My driver's side window is ignoring the top & bottom stop positions, if I let it the motor runs until the window is fully hard up or hard down, when it makes a godawful clattering noise as the motor is still running but the window can't move because it's fully up or down, so the teeth on the motor are jumping across the teeth on the regulator (and I've had it apart, the motor tooth plastic is obviously softer than the regulator, so the motor teeth are wearing-off, yeuch)


Full history

- 2010 Cayman 987.2

- last year, had to replace the regulator : window wouldn't raise or lower, clattering noise so had a look in the door and found the cable had frayed and snapped

- so fitted new regulator which was easy enough following youtube videos, getting the door card off was the worst bit

- all worked fine, window went up and down; obviously window memory had cleared so I used the reset feature of winding window fully up and fully down to its limits so it 'remembered' where the up & down stop positions are : great !

- all worked fine for 8 or 10 months : window dropped on opening door handle and raised on closing door just as it should, window went up and down using one-touch just as it should, it stopped at the bottom and at the top

- but a few weeks ago, went out in car and then when getting back in and driving home was aware of 'window is open' wind noise so pushed button to one-touch raise it and sure enough wind noise stopped as window closed but then got the godawful clattering noise until I pushed button again to cancel the one-touch closing

- now, when I open the door the window drops fully 1 1/2" but doesn't lift back up when I close the door

- if I use the one-touch on the window in either up or down, the window moves but the motor doesn't stop running when the window hits its physical limits of open or closed, motor keeps running. godawful noise as teeth jump on motor vs regulator, until I hit switch again to cancel the one-touch

- so I can open and close the window by manually nudging it up & down on the switch, not using one-touch; so car is useable but obviously this is a pain as I've forgotten to close the window that 1 1/2" a couple of times after parking, or have forgotten about it and allowed window to go down fully using one-touch.

- and obviously every time the teeth jump, it's wearing them out

- I've had it all apart again, taken glass and regulator fully out and refitted it all back again, couldn't see anything awry, but it's no different still does it

- I can see that the teeth on the motor are being worn-off, as the plastic must be softer than the teeth on the regulator

- and I even disconnected battery for half an hour to see if a reset would make any difference : it 'forgot' the positions on the passenger window and I had to reset them, but driver's door still doing this


Any ideas ?


Where are the sensors for the window stop positions, which should cut the motor when it hits the full-up and full-down positions : are they on the motor assembly itself ?



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  • 1 month later...

Update (I hate it when you have a search to see if your question has been asked before, find it but there's no answer and you can't see what solution the other guy had !)


After a bit of thought I decided the issue was with the regulator, not the motor.

The motor actually works fine, it makes the window go up and down, it's not like the motor has died.

The regulator however is what I had replaced - the factory one broke (cable corroded and snapped) so I fitted a replacement : not a ££££ factory one but one which was sold as 'OEM' and was still significantly expensive rather than cheap rubbish, but rather less pricey ££.
Quality appeared as good as the original and it worked fine for 6 or 9 months (albeit with covid restrictions meaning not that much travelling about...)

Then it started with this issue where the motor didn't stop at the top & bottom of window travel, when the glass hit its limit the motor kept running and the teeth of the motor were jumping on the corresponding teeth of the regulator.
However, if using the window switch manually to keep away from the top and bottom limits and avoiding the one-touch up and down, the teeth still mesh and the motor drives the window fine.


Originally I was thinking I would need to replace the motor, which got very confusing because there are part numbers 997 624 181 and 182 (plus eg .01 .02 .03 on the end which is the revision/batch number)

- various breakers and sellers on eBay,etc are selling both numbers, sometimes as fitting driver's door and sometimes passenger door

- now I can see that maybe the driver's door one can be fitted to the passenger door as well and maybe have some redundant features [eg driver's door has switches for both windows but passenger door only has one switch for that window], but I don't understand how the passenger door one works both sides...unless maybe it was originally two models but Bosch rationalised production and just made one and badged it as two...dunno

- anyway, I took the door card off again and found that my motor is a 181 (driver's door, a RHD UK-spec car)


They way things work is that there is a conical plastic toothed male cogwheel on the motor, which fits into a corresponding toothed female plastic cup-shaped cog on the regulator.
On investigation, I found that this female cup-shaped cog is a bit loose in the frame of my regulator, so rather than just rotating and pulling the cable and moving the window up and down, I think when the glass hits the stop it was moving back a tiny amount and meaning that the two sets of teeth could now slip against each other - and the plastic of the motor cog is softer than the regulator cog plastic so it's wearing the tips of those teeth off.

What I've done - and we'll see if this is a long-term fix - is taken the motor and regulator out and filed a couple of mm off the mounting legs where they bolt together

- the motor is inside the door inner panel and the regulator is on the other side of it, there are 3 bolts going through from the motor, through the panel and into the regulator, pulling the two together and fixing them to the inner panel

- so I've filed (plastic - easy) just a couple of mm off both the regulator and the motor where these bolts go, so that the two are pulled that bit tighter together.

It seems to work, the motor now stops when it should, the one-touch works fine and the window stops when fully up / down, the auto-lift of the glass to seal into the doorframe works when you close the door.
As I say, we'll see if this is a long-term fix.


Edited by TTRider
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Good fix. I have just replaced my 987.2 o/s regulator with a new Porsche one. I realised it was a relatively common issue when they had one in stock.


I think the motor might be a generic VW one TBH.

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13 minutes ago, andygo said:

I think the motor might be a generic VW one TBH.


Oh I'm sure it is - but finding the right part number....


A quick look around on eBay and last-model Audi A3's use what visually is the same Bosch motor and you can even find one for less than a tenner, until you realise it's an offside rear from a 5door - and then you scrutinise the pictures and find it has a different number of pins in the connector....


Would a driver's door one from a 3 door work, or even a 5 door ? Dunno, but they're rarer and consequently more expensive (perhaps the fronts fail with all that dropping and lifting window lark every time you pull the door handle, rear doors don't get used much ?)


Under a tenner I was going to give it a go and shrug if it didn't work, but not at £40+ : I'd have waited for a Porsche one as I've seen them at £65

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