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9N3 Electric Windows Not Working

Go to solution Solved by joe005,

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Dont like to tempt fate but, how are your windows ?
I took the plunge about a week ago and replaced the relay and capacitor on the window unit pcb. I also resoldered the joints on a few of the larger surface mount components and a couple of connector 0v joints. I was surprised, as a reasonably practised solderer, how difficult it was to get the r & c off. The 0v connections needed a fair bit of heat, presumably because there must be a thick "ground plane" taking the heat away.
Touch-wood the windows have been OK since, time will tell !
Unfortunately the central locking is as intermittent as ever so I've still got work to do. 
I'm trying to fault-find the drivers door lock ie microswitches, via the wiring, before doing all the work to take it off but its a bit tricky when the car doesnt stack up with any of the the wiring diagrams I've got (including Joe005's unfortunately).
I managed to drag the part number for the drivers door lock (3B2 837 016 AA) out of my local VW dealer. Does anyone know part numbers for the microswitches ?


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Thanks for the measuring blocks data, this will be helpful. I did some more research and found the part number of my o/s motor is 6Y1959801, which showed up in a VW T5 forum and lot of people have ex

Hi, I’m a long time member and first time poster, as the last Polo we had was pretty reliable. My wife recently ‘upgraded’ to a Polo 1.4 SE 2006 9N3. It’s a 5 door auto with electric windows in the

Attached a picture of the Window Unit "Lash Up". Note the use of an old cup-a-soup carton to stop the "assembly" rattling ! With it mounted like this, it is possible to run the drivers window motor (


My windows have been running fine for a few weeks now, no sign of intermittent function and all seems good.  The drivers window is a fair bit smoother and faster than the passenger side, which I would say operates normally; I'm attributing this to stripping down the motor and lubricating the parts.


I'm fairly adept with electronics (studied electronics but only use it as a hobbyist these days) and I agree, the relay and capacitor were very difficult to remove.  I pilot drilled the cap holes and used a higher temperature and voltage rated cap (it had slightly thicker legs), probably not necessary, but it does no harm.  I also re-soldered all of the larger joints... I can't put my finger on what fixed it, but one of those things seems to have done the trick; it may have just been the relay and cap replacement.


Once you pull out the CL motor, you may be able to use switch cleaner and get it running again if the microswitch is just crudded up.  I'm not sure how, but I read that they can get pretty mucky and this affects operation.  Good luck!


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  • 3 weeks later...

Does anyone know the torque settings for

1) the two window glass clip/clamp bolts ie those accessed through the large holes in the door inner panel

2) the two door lock bolts ie those that hold the door lock to the door frame

3) the (20 off ?) bolts which hold the door inner panel to the door itself

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Thanks for the torque figures - I particularly dont want to crack the window glass !

Further to my post of 2nd May, I'm glad to say that my electric windows are still working.

Since then I've carried on fault finding my intermittent central locking problem.


Although the wiring in my car was different to the 9n1/3 wiring diagrams, I decided that the blue/white wire in the drivers door-lock loom was the lock control wire. Online research suggested that the current in this wire determines whether the door lock locks or opens. During a period when the central locking WASNT working (using the drivers door key), I found that shorting the blue/white wire to ground, successfully locked the door, whilst connecting the same wire to ground through 120ohm  successfully opened the door.

I deduced that the door lock itself must be at fault. Because the cars courtesy light was working fine, I decided that the door locks "external" microswitch was OK so it must be a problem with one or all of the "undercover" pcb-mounted microswitches. However, I was unable to find a source of these Cherry components so I was stuck. As luck would have it, though, a new VW door lock assembly appeared on Ebay and I "won" it. So I decided to bite the bullet remove the door inner panel and replace the whole lock assembly.

Success ! Hooray !

Just to be sure, though, I think I'll wait a couple of weeks before replacing the door card !


NOTE: Whilst trying to find a source of the Cherry microswitches I came upon a very useful link:


by VWVortex Moderator, Gary Thompson PH.D. In addition to describing a similar (Jetta) lock and its microswitches, the document indicated that failure of the solder joints on the door lock connector has produced similar faults to microswitch failures. I was hoping that this may be the cause of my problems (particularly as I hadnt found a source of the microswitches) but in the end I didnt have to strip the old lock down. I'll save that job for a winters day when I'm stuck indoors - I am interested to know what the fault was.


PS: Does anyone know a source of new, reasonably priced, electric mirror switches - 
6Q2 959 565H ?

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  • 4 weeks later...

Monthly Report


All back together now !


Windows and Central Locking still working BUT...........


Over the last couple of weeks a problem has developed with the "feel" of the drivers lock (it didnt do it after the initial fitting). When locking the door, if the key is turned more than about 45° it "feels" as if the barrel of the lock is catching/binding on something  and something is about to break. I've had the barrel out and checked / WD-40'd it, but it doesnt have the problem on its own. I've also checked / WD-40'd the white plastic rotating part of the lock unit itself which mates to the barrel. Again no problem. I'm beginning to wonder if something is catching within  the lock unit (the motor drives some plastic cams etc) and this is felt in the key. However, to look at this means taking the lock unit out again... aargh!

The latest thought I've had is whether there is a "timing" problem with the electrics.

Does anyone know if I should have re-coded the system (?) after changing the lock - it is the correct latest part number but not the number on the unit which came out of the car.


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  • 8 months later...
On 28/04/2016 at 21:43, joe005 said:




As of today the windows have both been working for over a week following the replacement of the ACT 512 relay and 100uF capacitor and a clean and lubrication of the motor (not sure if this was necessary for the repair).


I've been checking both windows each drive and drive and this seems to have resolved the issues.

hi ,

where can i found them please !!! i have the same problem :(

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22 hours ago, suisspal said:

hi ,

where can i found them please !!! i have the same problem :(



You can find the details of the repair with photos in my post below:-


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  • 1 year later...

+1 for this post, just wondering if there have been any updates on this Joe? tried the same, replaced the capacitor for 100 uF with 50V rating, everything worked for about 10 seconds and then stopped, and now cant get anything to fire up after replacing fuses etc. I went on to change the relay although i don't think it will be at fault, hasn't given any progress however.


VW dealership quoting £170 for a new part, and the car is definitely not worth spending that amount of money on! between a couple of forums this seems to have worked for several other people as well though so good work i guess, just not doing it for me though. Will have to keep hunting through fleabay for a replacement with the 6Y1 part number!


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  • 1 month later...
Guest Dyhve Brake as we?
On 07/03/2016 at 12:13, nige8021 said:

First Welcome to the forum.

Here's the wiring diagrams

9N3 Conv 1.pdf

9N3 Conv 2.pdf

9N3 Conv 3.pdf

9N3 Conv 4.pdf

9N3 Conv 5.pdf

9N3 Conv 6.pdf

9N3 Conv 7.pdf

9N3 Conv 8.pdf

9N3 Conv 9.pdf

9N3 Conv 10.pdf

9N3 Conv 11.pdf

9N3 Conv 12.pdf

There is a coding shown on your list for 4 power windows 00256

If you go to the coding on the module you should get a drop down menu that lists all the relevant options

90% of all VW door electrical faults are broken wires in the flexy rubber tube between the door and body


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  • 10 months later...
On 11/03/2016 at 18:18, joe005 said:

This afternoon I opened the drivers door and tested all the wires going into the motor, all were fine.

I pulled the fuses for both windows and when I put them back, the passenger side window worked, but only from the passenger side switch; drivers side still not working.

After locking then opening the car, the passenger window ceases to work, until I pull the fuse and replace it, then it works again.

Any ideas?

You will definitely need to replace the drivers side window motor this control unit does the job also for the passenger side also tried & tested myself yesterday as I have few polos for spares

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  • 1 year later...



First, excuse my English to which I asked my friend Google translate to help me.

Second, thank you for initiating this thread that I read more than once to make sure I understood everything correctly.

I had a similar problem with my VW Polo Smile (1200cc_64hp). My Polo is from December 2004.

So, after having read everything I decided to replace the 100µf capacitor (I used a 50V instead of 35V because there was nothing else in the store) and the ACT512 relay on the controller of the window mechanism, driver's side.
And, bingo, I can again raise and lower the windows of the front doors (at the rear the system is manual).

Also, I couldn't activate the central locking from the driver's door any more and now it works again. I have no idea if there was a bad contact somewhere and when taking it apart and putting it back together "something got back in place" or replacing the above mentioned parts helped to solve this problem as well.

So, I am very happy and I can never thank you enough for this very interesting thread especially joe005 and Hobby2016.


Best regards from Brussels.

Edited by Bequin
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  • 2 months later...

Very interesting thread, and my congratulations to those who have contributed.

I've been looking at these units myself lately, although I don't currently have an issue.


I've spent some time trying to reverse-engineer the little circuit boards, and have a few observations that may be relevant.


Firstly this only applies to the parts with numbers 6y1959801, 6y1959802, 6y2959801 and 6y2959802.  These four parts cover left and right sides for each of LHD and RHD cars with front electric windows. I've not looked at the variants that include rear electric windows. 


On later MK1 Fabias (sometime mid-2004 on) where these were first used I think, they are mounted a different way round, such that the part numbers make more sense on them than they do on the 9N3.  The third digit being a 2 would normally signify a RHD part, and the last digit being a 2 would normally indicate fitment on the RHS of the car, so on a RHD Mk1 Fabia 6y2959802 is driver's side unit , 6y2959801 is passenger side. 


Due the units being mounted differently compared to mk1 Fabia when used on Polo, Mk2 Fabia, Transporter and Skoda Roomster, all of these have the opposite, 'seemingly wrong' part allocation, where 6y1959801 is RHD driver's side etc. Everything is opposite.


If the third and last digits are the same (both either 1 or 2) it's a master (driver's side) unit, if they are different then it's a slave unit for the passenger side.  


They are connected to each other (and no other control units) data-wise  by the LIN bus system which is implemented  by the chips on the boards. Previous generations used CAN bus, LIN is cheaper...


The chip that does most of the legwork on these boards is MC33689 (suffix DDWB on the two units I've looked at so far) the sticker with what looks a bit like a QR code usually covers the top of the chip in question.  This chip directly powers the relay coils, generates the LIN comms stuff, and even supplies the 5V rail for the square microcontroller chip next to it.

Datasheet can be found here: MC33689, System Basis Chip with LIN Transceiver - Data Sheet (nxp.com)


A week ago I came across a supplier of these chips on ebay that included the word 'vulnerable' in the listing title, but no further details about what the vulnerability might be.


Then I found this: MC33689, MC33689D Device Errata - LIN Dominant Issue/Low Voltage Reset Weakness (nxp.com)


I can't help wondering if the 'deep' problem with these units all stems from one or both of these built-in hardware flaws, and that the fixes involving replacement relays and capacitors may just be improving the local voltage conditions such that the inherent weaknesses don't show themselves as often or at all? 


There's a newer version of the chip - MC33689DPEW - that may be a drop-in replacement, I'm awaiting one in the post to try on a faulty board.

It's non-trivial to change the chip, but potentially a hell of a lot cheaper than buying a new module from the dealer.  This latest chip version is probably what comes on a new-bought-today replacement, but I don't fancy buying one just to see. The suffix DDWB chip can't be ordered new from the manufacturer. (See revision history section at the end of the datasheet).


Anyone with a unit manufactured in the last few years (2014 on, say) brave enough to peel back the sticker and see what chip is on there? 






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  • 3 months later...

Well that stuff relating to the MC33689 chip turned out to be a dead end;  units which worked intermittently before changing that chip for the latest revision still misbehaved afterwards. 😒



I've just recently found something that may actually be a fix, but I'm not confident enough about it to say "Eureka" just yet. Not capacitor, not relay, not general re-heating of any bits. 


I would be keen to hear from anyone with a unit that's currently misbehaving, or one that has been removed from a Polo for such unreliable operation. 

Free attempted fix and return if you'll send it to me.

Needs to be in that state where it works, but then 'dies', then recovers for some (brief) period of time after main permanent feed fuse removal or full loom disconnection/reconnection.


I've only looked at 6Y1959801 (RHD Polo driver's side) and 6Y2959802 (RHD Mk1 Fabia driver's side) in any detail so far, but I think those two numbers cover most of the problem units. 


PM me please if interested.

Edited by Pete1
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  • 3 weeks later...

Hey, we have an 05 9N3. Windows weren't working when I bought it about a year ago, so we did the relay/cap fix on the driver's side. That worked for a little bit, although it was occasionally intermittent (given what was said about the chip crashing at low voltages a few months ago I figured it might be related to the battery being a bit lower on power after sitting for a while or doing some short journeys, but I guess not).


Unfortunately we went for a day out yesterday and the driver's side controls weren't working at all, but for some reason the passenger side was able to lower that window. Of course, by the time we actually got there it failed to wind it back up again 🙄 Cue an hour stuck in a supermarket car park trying to get the door card off and wind it back up using only what we could buy in the supermarket.


Don't really know what else to try at this point, you can get some "universal" regulators from china for about £15 but I'm not sure that would work with the software code weirdness. Depends when the 12v power going to the regulator is live, but I couldn't even find a pinout for the connector.

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Quick tip if your windows go screwy, you should be able to open or close them by putting the key in the door and holding it to the lock or unlock position

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