Key sync issues with having only one key and VDCS use.

carbore

carbore

Member
Hi,

My little project car only has one key and the key doesn't "blip" the car. I checked the battery and replaced with a checked battery and have tried every key sync process I can find on the forums.

The car was sold wiht the fault described as "Passed MOT with no issues but shortly after developed an electrical fault (new battery draining / alarm going off as soon as door opened (rather than delaying) / central locking activating when driver’s door closed from inside)"

However I have not been able to reproduce this fault, provided I unlock the car and then put the key in the ignition its file. If I wait then yes the alarm goes off but thats probably expected as the door key isnt disabling the alarm but the ignition does. (is that right?)

Anyway...

Is it expected that a single key wont sync e.g if its not a master key or all syncs are lost?, I seem to see stuff about VCDS being the "last resort". I do have a VDCS cable from when I had a Golf years ago but I have the "lite" version of the software. If I buy the full version should the key sync work as per the method here https://www.ross-tech.com/vag-com/cars/vw-remote-matching.html or do we suspect the lack of "normal" sync means I should be looking for other issues. I dont mind too much investing in the registered version of VCDS as im in for the long haul on the A2 so its probably worth it, but equally if I can keep it cheap.

PS yes, ill get a spare key too, cant stand not having a spare.

Thanks.
 
Sounds like a CCCU fault to me. A VCDS scan (even lite) should help to ensure its faulty . It’s the unit located under passenger footwell.
 
Another cheap thing to try is disconnect BOTH battery terminals. Then touch the 2 LEADS together to dissipate any residual power. Then reconnect the battery making sure the terminals and the connections to the black box to the left of the positive terminal are all nice and tight.
Yes when you open the car door lock using the key the alarm is not disabled that is why when you put the key in the ignition it cancels the alarm, if done quicly enough the alarm does not go off.
 
Just a thought on your long term aim to add a second key and the Ross-Tech link. I remember Steve Birchall reported that the Ross-Tech instructions contain an error and his modified instructions that many people have successfully used is here..

Adding additional keys- including the new shape key

Hi I thought a summary of the various options might help. To re-pair a key that has stopped unlocking / locking remotely. This one is an easy one. Just switch on the ignition and then press the unlock button on the key that has stopped working (as long as the battery is not flat in the key...
www.a2oc.net www.a2oc.net

Andy
 
Hi thanks for that info. I finally had some "quality time" with the car again this evening.

@PaulA2
I tried to scan the CCU for faults, whilst VDCS detected/connected to the CCU it would not complete a faut scan. It just sat there with an egg timer. Other Modules have scanned so its not the cable/pc. This is "interesting" and may indeed point to CCU.
Also I pulled the floor and inspected the CCU are, no visible signs of damage or water ingress but diddnt expect anything obvious like a pulled out connector. Note all the other central locking functions work fine e.g. off the lock and via the buttons on the drivers door. Does the CCU do all those, if so it would seem odd for such a selective failure? (maybe?)

@audifan
The battery terminal thing but it diddnt work, this is a process that us Discovery 3 owners (my daily car) are famillier with for a few issues but sadly it wasnt the answer on this one. I partly wonder though if the previous owners issue was fixed by this as the car was totally flat so it may have self cleared something whilst it was dead on the drive.

@Andrew
Nice link, I tried but VCDS complained about not being registered when I scanned group 21.

Overall the car is booked for MOT next week so ill see if the garrage (my trusted local family run place) can read it and reprogram. If not ill invest in VCDS. Im waiting for the MOT to find out how much other stuff I might need to fix to get the car back to a usable state.

Thanks for the help so far.
 
Perhaps worth trying disconnecting all connectors and scanning again. Sometimes minor corrosion can cause problems.
 
What was the last letter on your CCCU? the most reliable one is an AF unit, some of the early ones tend to become faulty after a few years...This could be your culprit and if it is a single letter then even more suspicious...
 
HI @Clackers If thats the long number above the barcode then its E, my car is X reg and has no listed history of replacement (lots of other bills) so its undoubtley an early CCCU.

@PaulA2

Bad news today is that last night I disconnected the batter and then the CCCU to leave it off for 24H as per this thread https://www.a2oc.net/community/inde...king-stopped-working-suddenly-resolved.38122/ rather annoyingly the car is now doing the original fault in that the alarm sounds as soon as the door is opened and previously when I locked it the alarm LED on the door was on in a way that appeared correct. My car had now owners manual (one on the way) so im not 100% sure of correct behaviour but its looking like its got worse.

Ill leave this until the MOT and see if the garrages test kit can get anything fixed or at least fault code.

If i buy a CCCU then should It program up off VDCS (paid one), I assume so.
 
carbore said:
HI @Clackers If thats the long number above the barcode then its E, my car is X reg and has no listed history of replacement (lots of other bills) so its undoubtley an early CCCU.

@PaulA2

Bad news today is that last night I disconnected the batter and then the CCCU to leave it off for 24H as per this thread https://www.a2oc.net/community/inde...king-stopped-working-suddenly-resolved.38122/ rather annoyingly the car is now doing the original fault in that the alarm sounds as soon as the door is opened and previously when I locked it the alarm LED on the door was on in a way that appeared correct. My car had now owners manual (one on the way) so im not 100% sure of correct behaviour but its looking like its got worse.

Ill leave this until the MOT and see if the garrages test kit can get anything fixed or at least fault code.

If i buy a CCCU then should It program up off VDCS (paid one), I assume so.
Click to expand...

This would be normal behaviour if unlocking with the key? If not I’ve had this on a car. I did the programming on mine by using the technique of turning on ignition then opening the windows then locking and unlocking with the key manually then pressing unlock on the remote, took a number of goes.


Sent from my iPhone using Tapatalk
 
Edwrai said:
This would be normal behaviour if unlocking with the key? If not I’ve had this on a car. I did the programming on mine by using the technique of turning on ignition then opening the windows then locking and unlocking with the key manually then pressing unlock on the remote, took a number of goes.


Sent from my iPhone using Tapatalk
Click to expand...
I'm sure there must be lots of different ways to re sync, but I have found the most effective way is to turn the ignition on to the second stage, press and hold the unlock button, turn the ignition to off, remove the key and then release the unlock button, the hazards should flash to tell you that the key is sync'd....worked every time for me....
 
Clackers said:
I'm sure there must be lots of different ways to re sync, but I have found the most effective way is to turn the ignition on to the second stage, press and hold the unlock button, turn the ignition to off, remove the key and then release the unlock button, the hazards should flash to tell you that the key is sync'd....worked every time for me....
Click to expand...

Yes this is the normal way but I had a car that just wouldn’t sync so I had to do the new key sync method using the internet external door lock


Sent from my iPhone using Tapatalk
 
Edwrai said:
Yes this is the normal way but I had a car that just wouldn’t sync so I had to do the new key sync method using the internet external door lock


Sent from my iPhone using Tapatalk
Click to expand...
Well every day is a school day sir, thanks for this, I have read so many different combinations, but bow to your superior knowledge(as always), and will store that in my GCE memory bank....any youngsters will wonder what a GCE is and think I didn't put the S in it!!!! Lol
 
Update on this one, the car had the MOT today and a code read while I was there. The garages reader wouldn't read the CCCU either so we can call it "dead" and I have a new one on the way. Ill update when it arrives.
 
Fitted an AF CCCU and its looking good so far as its not gone flat over a few days. Diddnt manage to sync the key with VCDS so need another go with a few of the guides handy. Fingers crossed the CCCU was the original fault on the car.
 
carbore said:
Fitted an AF CCCU and its looking good so far as its not gone flat over a few days. Diddnt manage to sync the key with VCDS so need another go with a few of the guides handy. Fingers crossed the CCCU was the original fault on the car.
Click to expand...
Evening,

This thread that Steve @Birchall put together a few years ago works perfectly for me when I’ve had to swap CCCUs or want to add additional keys.

Kind regards,

Tom
 
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carbore said:
Fitted an AF CCCU and its looking good so far as its not gone flat over a few days. Diddnt manage to sync the key with VCDS so need another go with a few of the guides handy. Fingers crossed the CCCU was the original fault on the car.
Click to expand...
Did the replacement AF CCCU come with the bottom half of a key? - Andy
 
To add the keys you MUST follow this guide to the letter.......

Adding additional keys- including the new shape key

Hi I thought a summary of the various options might help. To re-pair a key that has stopped unlocking / locking remotely. This one is an easy one. Just switch on the ignition and then press the unlock button on the key that has stopped working (as long as the battery is not flat in the key...
www.a2oc.net www.a2oc.net

Read three times, have a cuppa and read again so you know the correct order to do things in.
 
carbore said:
Hi @Andrew no i just got the cccu. I thought i could sync the key with VCDS Lite (registered copy)
Click to expand...
Hi,

First a word about terminology. I think the key system works like this, every key when you press the key transmits a unique code, like a bank PIN number. In the case of key new to the CCCU it has to be taught this new key is bona fide and to obey it. (Otherwise we could all unlock each other's cars!) This is done with VCDS and is called PAIRING (the key with the CCCU). Follow Birchalls's 'How To' guide to do the pairing. The new key has now got to be SYNC'ED using the procedure in the handbook basically to establish locked/unlocked state. Sorry to be pedantic and I hope I got that lot right.

To answer your question VCDS Lite can pair new keys.

The only reason I asked about the key is I know if the key transmitter frequency does not match the CCCU it will never work. The key's transmitter frequency in MHertz is normally on the key and visible if you seperate it into two halves as when replacing its battery, procedure in handbook. How you check the frequency of the CCCU I do not know, printed on case??, in the German definitive PDF?? Somebody will know. CCCUs sourced here on the forum normally come with the bottom half of the key to guarantee compatibility and be already paired.

Not to worry.

Andy
 
HI, Thanks @Andrew pedantry on terminology is welcome!

Im now stuck though. I tried Birchall's guide and the RossTech approach to no avail. I get all the right menus via module 46, Adaptation, then pick the number of keys but I do notice that the field at the top never says "initialising". Is it supposed to say that when its "listening" for a new key or does it only say initillising when it "hears" a new key.

I ask the above as I only have the one key that came with the car bought with this fault, I have no way of knowing if they key is not damaged or now if they key is actually the wrong frequency. I have changed and tested the battery on the key too.

Another issue is the CCCU "coding" the new CCCU says soft coding is 6859 but the old one was 0185 could that be it.

Im not sure what to try next.

The only good news is the battery drain fault that made the seller "give up" seems to have gone.
 
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