Driver side locking unit can't lock rear driver door turned into no door locks

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GianSeven
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Driver side locking unit can't lock rear driver door turned into no door locks

Post by GianSeven »

Premise, I'm italian so the car is left hand driver so for me right is driver side and left is passenger side.

Hi, I have a 1.4TDI 2008 9n3 which had issues to the central locking unit in the driver door, basically the locks all worked if the passenger side lock or button on driver door was used but if you tried to lock from the driver side the rear passenger stayed open (but always locked). The car doesn't have the remote. This happened mostly only when there was heavy rain or there was high humidity for a long period of time. So some weeks ago my father and I decided to remove the door panel, check all connectors and open the central locking unit itself to check the circuit (the one inside the driver door window unit) but it all looked good besides some carbon buildup from the motor brushes. Of course it did nothing and once it rained again the problem was still there. Fast-forward 2 weeks and without any rain or humidity now no door except the driver locks, I hope it's something I did and anything else broke. What could it be, wires? Should I replace the window motor unit?
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Maarten
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Re: Driver side locking unit can't lock rear driver door turned into no door locks

Post by Maarten »

Check the door bellow of the drivers side.
Could be a broken or stripped wire there.

Does the button inside the car work to lock all doors?
Hold the key in lock open position, do all electric windows go down? Or just driver side?
Last edited by Maarten on Thu Mar 16, 2023 9:30 am, edited 1 time in total.
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Maarten
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Re: Driver side locking unit can't lock rear driver door turned into no door locks

Post by Maarten »

Why change the window motor?
GianSeven
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Re: Driver side locking unit can't lock rear driver door turned into no door locks

Post by GianSeven »

Maarten wrote: Thu Mar 16, 2023 9:27 am Check the door bellow of the drivers side.
Could be a broken or stripped wire there.

Does the button inside the car work to lock all doors?
Hold the key in lock open position, do all electric windows go down? Or just driver side?
The button inside locks everything. The window all go down when the key is held in the unlock position
Maarten wrote: Thu Mar 16, 2023 9:29 am Why change the window motor?
The window unit is called "Driver side central locking unit" in VW service manual because the door go through it to communicate to the comfort unit inside to lock all doors, or at least that's what I understood from the diagrams and testing

Here are some pics I forgot to post
https://imgur.com/a/tCIXlQM
(I wasn't able to use the integrated photo host)
6Q2959802F is the unit
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Maarten
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Re: Driver side locking unit can't lock rear driver door turned into no door locks

Post by Maarten »

Okay.
Seems that the doormodule is working fine, for the windows and the inside lock button.

Do you have a VCDS tool available?
You can check the lock statusses in messurement blocks, statusses are OPEN, LOCKED or UNLOCKED
You can check for any DTC's (faultcodes) in the controle modules
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Re: Driver side locking unit can't lock rear driver door turned into no door locks

Post by GianSeven »

Maarten wrote: Thu Mar 16, 2023 10:30 am Okay.
Seems that the doormodule is working fine, for the windows and the inside lock button.

Do you have a VCDS tool available?
You can check the lock statusses in messurement blocks, statusses are OPEN, LOCKED or UNLOCKED
You can check for any DTC's (faultcodes) in the controle modules
Unfortunately I don't have VCDS tool, they cost too much for what this car is going to last me (I'm cheap) and I've checked around for mechanics who could check but they won't do it if they don't fix the car too. Is this anything I can check with a multimeter on the LIN/CAN bus in the output pins?
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Maarten
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Re: Driver side locking unit can't lock rear driver door turned into no door locks

Post by Maarten »

No, I don't think that's possible.
You could get one from AliExpress for as little as 30euro's, but maybe there is a forum member that lives in Italy who has a scantool.

For now I would check the door bellows for wires that maybe broken or almost broken or with poor insulation so they won't have a good connection.
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Re: Driver side locking unit can't lock rear driver door turned into no door locks

Post by GianSeven »

Maarten wrote: Thu Mar 16, 2023 11:06 am No, I don't think that's possible.
You could get one from AliExpress for as little as 30euro's, but maybe there is a forum member that lives in Italy who has a scantool.

For now I would check the door bellows for wires that maybe broken or almost broken or with poor insulation so they won't have a good connection.
I'm still too cheap, I think I'm going to remove both panels and use my multimeter to check what is happening at the pins, I have the electrical diagrams I just have to trace them hopefully. Is it difficult to remove the metal panel covering all the other stuff? Anyway as of today the unlock from the driver side doesn't unlock anything anymore but the window and buttons still work
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Re: Driver side locking unit can't lock rear driver door turned into no door locks

Post by Maarten »

Could still be a faulty lock.
Connector is behind the metal plate.

The metal plate can be removed after:

removing window / or fixing it on the door with tape
all m10 bolts
2 plastic pins off the doorlock / or loosen doorlock
disconnect all wire connectors
some wires have to be pushed through their holes

Doorpanel is pretty straightforward
remove bottom torxscrews
remove front of doorcloser, behind are 2 torx screw
pull gently from bottom towards yourself.
Plastic retainers have a tendensy to break easy, so use plastic tools or buy spare ones
release the doorlock inner cable

There are lots of turtorials on youtube
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Re: Driver side locking unit can't lock rear driver door turned into no door locks

Post by GianSeven »

I got around to removing the door lock module and opening the unit itself, but during the dismantle some plastic piece inside was falling apart and got destroyed, the module wasn't anymore unlockable by the interior handle and by the lock cylinder so I got a new unit and replaced it (part number 3B1837015AQ). I only had good sunny days since I changed it so if it'll stop working again during rain or cold weather I'll update this thread
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Maarten
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Re: Driver side locking unit can't lock rear driver door turned into no door locks

Post by Maarten »

So faulty lock, good you found the issue.
Keep us posted!
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Re: Driver side locking unit can't lock rear driver door turned into no door locks

Post by GianSeven »

Update in case someone comes across this thread in the future
The problem with the locks was fixed. All the locks work under every weather condition now but the alarm LED is still not turning on. I think it's an unrelated problem. (The diode itself works, tested with a multimeter, it just doesn't receive any voltage)
Anyway possibly all that is needed to fix the faulty door lock module is cleaning the microswitches, maybe the one attached with wires on the outside is enough (there are four more inside), it's not too difficult to do but my unit had a piece of the internal handle mechanism falling apart and during the reassembly it gave out therefore the door wasn't openable from inside anymore so I had to get a new one for that.
With cleaning the microswitches I mean opening them and spraying the inside with contacts cleaner or simple isopropyl alcohol that won't damage the plastic casing
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Maarten
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Re: Driver side locking unit can't lock rear driver door turned into no door locks

Post by Maarten »

Yes you can try cleaning the switches.
Alarm led is related to the status of you lock microswitch.
Maybe you have to replace the lock in the future.

Thanks for the update!
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