Key issue

[Passat my07]

Hi, one of my keys is playing up. The unlock button won't work. It still starts and locks etc. I think the micro switch has failed. Has anyone split a key open and replaced one of these? I took the back off and changed the battery but it didn't help. It didn't look easy to get the guts of the key out. I do have a spare key from our old Passat so I can try with that one without destroying the good key.
Thanks

[Guest001]

Keys are paired to the car as far as Im aware. A new one has to be coded in ( B7 anyway)

[kamold]

You can replace the microswitches without having to play at all with the transponder or adaptation if you are handy with a soldering iron.

[Passat my07]

I was planning on replacing the micro switch. Has anyone done it? Maybe you have to destroy the clear plastic part to get it apart? You can buy a shell off eBay and it includes the clear plastic bit. You can also buy the micro switches separately.
Thanks for the replies.

[kamold]

There are videos on how to dismantle

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[D13S3L]

Apparently it's glued together but can be carefully split to access the guts of it. From what I've read, keys can be coded to the car quite easily, however don't take my word for it as I'm not 100% and that just seems too easy to be true. Think there's a few videos on youtube regarding opening the fob and also coding it to the car.


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[kamold]

A brand new key requires either the dealer to code it to your VIN, or you need to do the following:

1. Remove the CCM from behind the glovebox.
2. Read out the EEPROM which contains the immobilizer code to a file.
3. Decrypt the secret key code (SKC) from the EEPROM dump.
4. Code the new key using FVDI or similar and a suitable adapter
5. Update the CCM file with new key info
6. Re-write the newly modified CCM EEPROM and reinstall CCM
7. Run key adaptation from VCDS or similar

It's certainly doable but you need to have all the right tools and software, some of which is quite expensive.
An automotive locksmith can do all this for you.

Of if the key just needs new microswitches just replace them, much easier and cheaper.

[D13S3L]

^^^ damn! Glad I read that before I went ahead and bought myself any spare keys.
Now that I thought about it, I was thinking of pairing the key back to the car in instances where battery goes flat or stops responding, etc. would explain why it's easier because it's already coded correctly. My bad :s
Complete fobs on eBay were going for just under $200 I think. Add on cost of coding and it seems like a pretty expensive task. Here I was thinking my replacement Ford key was a rip @ $125...


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[Passat my07]

Thanks everyone for your help. I got it sorted tonight.
I started with the spare key from our old car. After taking the back off the key and removing the battery I sliced the long clear plastic flat bits on each side with a razor blade. Then at the unlock end of the key I slid a knife between the clear part and the black part and twisted it to split it open. (You need to be careful not to damage the circuit board). I then took the micro switch off the board with a soldering iron.
I then put all the parts from the old car in a bag so I wouldn't get them mixed up with the good key. (I think you can get into trouble if you put a key from another car in your ignition)!
I then split the good key and swapped the good micro switch I had stolen from the other key onto this one. I tested it and it does everything it should. I just need to get some superglue now to refit the clear plastic bit properly.

[kamold]

Thanks everyone for your help. I got it sorted tonight.
I started with the spare key from our old car. After taking the back off the key and removing the battery I sliced the long clear plastic flat bits on each side with a razor blade. Then at the unlock end of the key I slid a knife between the clear part and the black part and twisted it to split it open. (You need to be careful not to damage the circuit board). I then took the micro switch off the board with a soldering iron.
I then put all the parts from the old car in a bag so I wouldn't get them mixed up with the good key. (I think you can get into trouble if you put a key from another car in your ignition)!
I then split the good key and swapped the good micro switch I had stolen from the other key onto this one. I tested it and it does everything it should. I just need to get some superglue now to refit the clear plastic bit properly.

Nice work
The microswitches are invariably going to fail through use.
And the external housings get beat up.
So you can buy a blank key to use the housing and then transfer the transponder, emergency key and PCB, and replace the microswitches (either from the new blank, or just generic) and you'll have a new key.

If you are missing a key and want a pair, unfortunately you have to incur cost either with a dealer or good auto locksmith. The security is there for a reason

[D13S3L]

Has anyone purchased one of those blank key/housings before? Curious if they come all split so you don't have to pry open the internal plastic, or if they're already glued (would seem silly if it was).


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[kamold]

I actually have some on order should have them next week. I'll let you know.

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[D13S3L]

Sweet thanks Kamold appreciate it


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[kamold]

Got my new blank keys.
They are fully assembled, but they are not glued at all.

Easy enough to disassemble in order to swap over the transponder and PCB (if you just want a new housing) or to get at the microswitches if you want to replace them. The original key is harder to pull apart as its glued. But it doesn't matter so much if you damage it given you're swapping the housing....

Here is the original housing, with new blank emergency key, glass transponder and new PCB. I swapped the originals into the new housing.



Optional:
If you have access to VCDS, the ONLY parts you need to keep from your original key is the little glass capsule that contains the transponder and emergency black plastic key. Handle the transponder with care!
Leave the car unlocked, or have your second key available.
Once you have transferred the transponder into the new key housing with new PCB, you need to run key remote adaptation in Address 46 Central Convenience.
Erase keys and then relearn all available keys per the procedure in VCDS.

I've just done this successfully.
Have a brand new key now, with new clicky microswitches.

Reference in German, use google translate:
Passat 3C Funkschlüssel zerlegen – dunt.at

Check this video for key disassembly:
[YOUTUBE]taC2LYFhPW4[/YOUTUBE]

[kamold]

Note that the quality of the key blanks seems to vary.
I swapped and adapted one for another owner today and the plastics were not of the best quality, didn't fit together as well and the top silver cap was plastic rather than metal.
I got this one and am very happy with the quality:

https://www.aliexpress.com/item/3C0959752BA-433Mhz-48chip-auto-smart-card-3CO-959-752-BA-car-key-smart-key-for-VW/32639074162.html