# Repairing the Access and Start Controller (controller 07) - resolving antenna 'open circuit' faults [TOC done]



## Jorgsphaeton (Sep 8, 2009)

I want to replace my keyless access module, the one under the driverseat. can I copy the old settings into the new one with VCDS and without dealer interference?

thanks jorg


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## PanEuropean (Nov 3, 2001)

No. The 'Access and Start Controller (controller 07) works in very close co-operation with the engine controller(s) and the instrument cluster to operate the anti-theft system.

When any of these three controllers are replaced, the car must be at a VW dealer and hooked up to the VW corporate internet, and reprogrammed from there.

It is also essential that all of the keys for the car are present at the time any of these modules is replaced. Any keys not present at the time of replacement (and reprogramming) will be disqualified from future use.

Michael


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## Jorgsphaeton (Sep 8, 2009)

*fix kessy yourself*

I found a solution for repairing the kessy unit, so I'm looking for a good electrician and a phaeton enthuasiast for fixing the kessy myself (in the netherlands), see this link:
http://www.clubtouareg.com/forums/f43/anyone-had-a-kessy-module-rebuilt-45716.html
or this:
http://www.clubtouareg.com/forums/f43/anyone-had-a-kessy-module-rebuilt-45716.html

thanks Jorg


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## PanEuropean (Nov 3, 2001)

Jorg:

Getting physical access to the controller is not difficult. See the post in the FAQ entitled "Retrofitting Keyless Start" - that explains and illustrates how to get access to the controller.

Having said that, though - before you start work, park the car in a position such that it can easily be loaded onto a flatbed tow truck (for removal to a VW dealer) in case things don't work out. I think you run a fairly high risk of failure here, because what you are trying to do (replace one of the controllers in the anti-theft system yourself) is a direct conflict with one of VW's primary design objectives when they constructed the anti-theft system.

Michael


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## dlouie (Oct 31, 2008)

Jorgsphaeton said:


> I found a solution for repairing the kessy unit, so I'm looking for a good electrician and a phaeton enthuasiast for fixing the kessy myself (in the netherlands), see this link:
> http://www.clubtouareg.com/forums/f43/anyone-had-a-kessy-module-rebuilt-45716.html
> or this:
> http://www.clubtouareg.com/forums/f43/anyone-had-a-kessy-module-rebuilt-45716.html
> ...


Jorge,
That's an interesting find. I'd do it in a heartbeat. You really have nothing to loose if you can verify that the Kessy is indeed bad. Heck, I'd do it for you if you were in the states. Please document as much as possible with your experiences for the benefit of the members.

Damon


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## WillemBal (Nov 20, 2010)

Hi Jorg,
I just replied to your PM. I could do this for you, but as I wrote, I would need to know which transistor is defective. Otherwise, I would need schematics, a component layout diagram and a functional board on which measurements can be done. I am about to read the second link you provided and if the procedure is detailed there, then it should be possible to do within a heartbeat as Damon said.
Looks like a good opportunity to meet one another and perhaps create the beginning of a Dutch Phaeton enthusiast club. :wave:

Willem


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## Jorgsphaeton (Sep 8, 2009)

I think I need all the components as mentioned in the threads, if the module is out of the car, I can't drive and it should be back in the car as fast as possible without any problems or removing it again because another component should be replaced. as I see I need 2 mosfets and 6 resistors.
I have a used kessy but I'm not sure if it works, because for installing I have to go to the dealer and they should install it with high costs, while I want to do it myself. So I should find these new mosfets and resistors in the netherlands before I try to remove the kessy. and I got an example so I will open it up this weekend.

on every VCDS error log it says:
fault on kessy 3D09089135L:
- open circuit on Antenna BZ for access and start
- open circuit on Antenna for passengerside
- open circuit on Antenna rear bumper for access and start
- open circuit on Antenna lugagecompartment for acces and start
- open circuit on Antenna 1 interieur for access and start

thanks Michael for your advise, I thought I will open it up in my garage but a tow truck can't reach till there.

thanks Jorg


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## WillemBal (Nov 20, 2010)

Hi Jorg,
What you need are indeed 2 MOSFETS. They are IRFZ24NS MOSFET's. 
You can purchase them from Farnell. Best buy 4 of them, just in case, however I can order them for you as well. We have an account with this supplier.
The fusible resistors are SMD type and as such hard to find. The alternative are traditional (fusible) resistors with leads. They have the same function, just the mounting of them is different. It won't be difficult to install them, though. Price is 0.08 Euro each :laugh:
Apparently, the Mosfet devices control the power to the various components. When they die, the VCDS cannot communicate with the KESSY. The antenna faults point into the direction of fried resistors.
Just send me a PM when you are ready for it, then I'll order the components.

Willem


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## Jorgsphaeton (Sep 8, 2009)

if you think that is better than the original ones you can order it. today I will recieve the ones mentioned on farnell

thanks
jorg


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## PanEuropean (Nov 3, 2001)

Hi Jorg:

Uh, just a clarification of the opinion I gave in post #2 above (in response to your question in post #1) - I had the impression that you were attempting to replace the Access and Start Controller with a new one, so, I responded that this was not possible without reprogramming that can only be carried out at a VW dealer. I still stand by this opinion - if the Access and Start Controller is replaced, it (and the engine controller, and instrument cluster controller, and vehicle keys) all need to be adapted at a VW dealer whilst the car is connected to the VW intranet.

It now appears to me - from reading this thread as it has evolved - that your objective is to *repair *the controller by replacing some 'low level function' electronic parts that don't perform logic functions. In this case, provided that the logic, the coding, the adaptation of the controller is not affected (and, from reading posts #3 to #8, that appears to be your objective), I think you should be able to repair the controller by replacing the parts that you and Willem have discussed without any need to re-adapt the controller and without encountering any unwanted effects to the anti-theft system.

Some suggestions, based on my past experience with this controller:

*1)* Depower the car by disconnecting both negative battery terminals prior to starting disassembly work. Basically, when the car is totally depowered, it won't generate fault codes, and it doesn't know what is being done to it. This will avoid any possible unwanted complications when you disconnect and reconnect the controller. There are a few tips to consider in the post Retrofitting Keyless Start to Phaetons that are equipped with Keyless Entry, for example, removing the driver seat retention bolts before depowering the car (so you can move the seat fore and aft to get access to the bolts), etc. Have a look at that thread carefully, it will save you headaches. Also, order 4 replacement seat bolts - the bolts that hold the front seats on are single use only. They are cheap.

*2)* After depowering and repowering the car (for any reason), you will need to "re-educate" a lot of moving components so that those components know the physical limits of their motion. There is a post in the FAQ How to adapt moving components (windows, seats, sunroof, trunk lid, etc.) explaining what has to be done and how to do it.

I have modified the title of this thread so that it reads 'Repairing the keyless access controller", rather than 'replacing'.

Good luck with your efforts.

Michael


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## Jorgsphaeton (Sep 8, 2009)

hello Michael,
the first idea was to replace it but after your suggestion I changed my mind and found this old thread about repair of the kessy. I think this is a solution for a lot of people.
hope it works. If I use the old seat bolts, is that a problem. I can use locktide to secure the bolts?

thanks jorg


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## Jorgsphaeton (Sep 8, 2009)

about the bolts, I don't need to remove the seat, I saw on the pictures that the kessy is in front of the seat. and I just tried to access the kessy and it is possible without removing the seat. just remove the sideplate, the deadpedal and fold up the carpet. it is tight but just enough to remove the two bolts of the kessy and remove the kessy unit. it is a ten minute job. 

thanks jorg


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## WillemBal (Nov 20, 2010)

*Yesss!!!! Succes!!!*

I'm very happy to announce the first (known) successful repair of a Phaeton KESSY on Jorg's car (with the help of a Touareq forum thread that he found). eace:
Two MOSFET's needed replacement and after clearing the antenna faults the keyless access function worked again. More details and photo's will follow soon.

Willem


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## dlouie (Oct 31, 2008)

Congratulations to all on this project. This is very encouraging.

Damon


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## Jorgsphaeton (Sep 8, 2009)

And it is still working perfectly! as told earlier you can access the kessy just by removing the side plate and the carpet, but be carefull with the carpet, at the bottom of the carpet there is a strengtened plate created in the carpet itself, it will tear the foam if you don't lift that plate while rolling up the carpet as told in the thread about the start/stop button.
as I think this repair could be done by everyone, just be carefull and be patient.

jorg


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## WillemBal (Nov 20, 2010)

*The KESSY repair procedure*

*Parking and KESSY removal*
First, we parked the car in a position such that it could easily be loaded onto a flatbed tow truck in case things went wrong, just as Michael suggested. Next, we unlocked the doors, moved the driver seat all the way aft, and disconnected the minus lead of the convenience battery.

Next, the carpet in front of the driver seat needs to be partially removed. To do this, some components need to be removed, i.e. the boot lid unlock lever, the dead pedal and a small part of the lower door trim, as in below picture:










Taking out the Kessy is quite easy this way, I just held the carpet up so that Jorg had both hands available to unscrew the two bolts and to unplug the two connectors.

*Disassembly of the KESSY*
Removing the board from its housing is pretty straight forward and once it is out of its housing, it is visible as in below photo. (Edited photo of ClubTouareg) 











*Replacing the MOSFET's*
The MOSFET’s are easy to identify, something which cannot be said about their proper functioning, because it needs power to perform any meaningful measurements. Trusting they were both gone, I just soldered both of them out and replaced them with 2 new ones. On the photo, the soldering job in action.









The smoke traces are of the No-Clean Flux I used, a product which enhances the flow of (lead-free) solder between component (the drain plane of the FET) and the copper plane underneath it.

*Fusible resistors*
On the back of the board, we found the 6 resistors which were discussed by some members on the ClubTouareg forum. As they reported, they are each 0.22 ohm fusible resistors and might all need replacement. I found 2 groups of each 3 parallel resistors. See below photo.










They seem to me like 0.33 ohm resistors, as each of them has been coded with two orange rings. Since I measured 0.11 ohm on each group (with a DMM capable of measuring such low resistance values), I concluded that they were all in perfect shape and didn't need to be replaced.

These fusible resistors are resistors which will act as a fuse when the power (x time) exceeds a certain limit. Fuses, with generally low resistance values, are not suitable since their resistance may not be constant with electric load. On the other hand, normal resistors may go up in smoke when a short circuit in one sensor or electronic circuit occurs while the same current is not sufficient to blow the controller fuse.
The advantage of *fusible* resistors therefore is that if an active component, such as the MOSFET’s, causes a short circuit, then the fusible resistors will go open the circuit, just like a fuse would do. Obviously, the FET’s died before the resistors tripped, so they are still in good shape - fortunately, as my soldering skills are too rusty for these tiny components.

*The seal ring*
Noteworthy is the seal ring, which apparently is there to prevent water ingress when the car is flooded with water. Perhaps we should have applied some “high vacuum grease” (Dow Corning product) or some other lubricant to help the seal do its job properly, however at the time we didn’t think about that. Besides, we were planning to wrap it in a plastic bag anyway, as suggested by some other members.

*Installation*
As usual, the installation procedure is the reverse of the removal. Back in the car, with the battery reconnected, we of course immediately tried to unlock the car by grabbing one of the door handles, without avail. Good old VCDS helped us out here. After the first attempt to clear the DTC’s of the controller, they didn’t return and then….Hallelujah! another miracle!…the door opened at the touch of a hand! And the other doors too. eace:

Conclusion is that it is possible to repair a faulty KESSY by using about 5 Euro worth of components and some soldering. :laugh: We spent the whole afternoon, mainly discussing various (other) issues, but I’m sure that the repair job may take as much as 45 minutes including removal and installation of the KESSY, provided that the technician who does the soldering has the proper tools and workshop for working ESD-safe. I hope that many other forum members with the same problems with their door handles (and KESSY related problems) realize that it is worth a try to repair it this way.

P.S. For those of you who are wondering what these components actually do:
The two power MOSFET’s are part of a “switch mode” power supply. Other visible components are the big blue capacitors and the large transformer. It converts the 12 Volt DC into various voltages, necessary for the electronics to function and to drive the sensors. It seems to me that this little circuit is still active when the car is locked, in order to give power to the antenna sensors (which sense the presence of the key in your pocket). So you can imagine that a faulty power supply can create lots of gremlins, perhaps even more than what a poorly charged battery can do.

Willem


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## Natebrown06 (Oct 4, 2012)

*What is in between the 2 Mosfets that need replacing?*

I have been attempting to repair my Kessy for an 04 Phaeton...I had an electrician do the soldering for the new mosfets...After doing so, he asked me what goes in between them... I am  
I do see that in between them, there is a space that it looks like something should go but on mine, it is empty. I am wondering if maybe i broke it off while cleaning it. What is the little link's function? Is there a way to replace it?

thanks,

Nate


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## StevenFT (Jan 26, 2012)

Looking at Willem's picture, it looks like there's a surface mount resistor between the back plastic MOSFET cases. It's been a month since I've had my KESSY open...so my memory is a little fuzzy. Willem can probably give you more insight than I. If it is the resistor, I doubt that it would have come off in any cleaning process unless you were using a screwdriver to scrape along the board.

Cheers,
Steven

As an aside, I'll be updating my own KESSY thread shortly. At that point, perhaps Michael will merge that one with this one if he feels the content is similar enough.


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## PanEuropean (Nov 3, 2001)

*Archival Note: * See also these discussions about the Access and Start Controller - Kessy and Keyless Access discussion, and KESSY Antenna Issues.

This post (Repairing the Access and Start Controller (controller 07) - resolving antenna 'open circuit' faults) has now been added to the Phaeton Forum 'Table of Contents' (FAQ by Category).

Michael


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## WillemBal (Nov 20, 2010)

Natebrown06 said:


> What is the little link's function? Is there a way to replace it?


The little link is probably a capacitor or a resistor. There is a way to replace it, but you would need to know the part number. It will be quite hard to find the SMD shape, but it should be possible to locate one with solid wires.



> I am wondering if maybe i broke it off while cleaning it..I had an electrician do the soldering for the new mosfets....


OMG. At least you can blame him now...

But seriously, is he familiar with (de)soldering SMD components and ESD protection? And why did you clean it? And what did you use to clean it, making you now wonder that it might have fallen off the board?

You may inspect the board between the 2 Mosfets with a good magnifying glass, to determine whether the soldering islands were unused. When there are no traces of solder on both islands, the component may have been omitted for some reason.

I have no plans yet to dive under the carpet to inspect my Kessy, but when I do so, I certainly will check to see what component it is and what function it might have.

Willem


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## PanEuropean (Nov 3, 2001)

*Archival Note:*

See also this discussion: Yellow Key Symbol on Combi Instrument Panel (KESSY photos and troubleshooting)

Michael


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## Jorgsphaeton (Sep 8, 2009)

*repair doorhandle kessy*

After almost two years with no kessy problems, my doorhandles seem to stop working one by one.
I'm almost sure it is a problem with water getting into the doorhandle, because they fail one by one after I washed the car, now I just got one left that is still ok. Did somebody repair the kessy handle, or is the only solution to this problem: replacing them?

thank
Jorg


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## PanEuropean (Nov 3, 2001)

Hi Jorg:

To the best of my knowledge, the only fix is to replace the door handles. Water gets into the handle and causes corrosion underneath the flexible rubber cover that you push to lock the doors - I am not aware of any way to dis-assemble the door handle to get access under this rubber cover. Chances are that even if there was a way to dis-assemble the handle, the damage caused by the corrosion might not be reparable. 

Michael


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## Jorgsphaeton (Sep 8, 2009)

in vagcom it says that I have a short to the ground in the doorhandle, so that could be water. 
I heated the handle to dry it so It would solve the short to the ground problem. 
but that was not the solution. I think, and maybe Willem can confirm, that because of the defective doorhandle, the fusible resistors are broken. 
if so, maybe we can replace them so that all the three other doorhandles will work again without replacing the expensive doorhandles. 
If I imagine the doorhandle button is just a simple switch, two metal plates that connect to eachother when pressed. when water is inbetween it looks like a very long press and the fusible resistor will open because of the high contant voltage it is getting. 
accessing the car is no problem it is just closing the car with the button, that stopped working. 
I just have one left. 
could it also cause battery drain? because after this happened the battery is low on voltage after a few days. 
charging the battery doesn't solve the problem. 

thanks Jorg


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## Paximus (Aug 26, 2011)

Hi Jorg, 

If the corroded door handle button is telling the controller that it is pressed all the time (ie permanently shorted) then probably the car is being held 'awake'. 

It will be running the security radio to get a response from the chip in the key fob that it assumes the person who is holding in the door button will have on their person. This will drain the battery. 

Chris


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## Jorgsphaeton (Sep 8, 2009)

thanks Chris, I removed the doorhandle knob and that solved the battery drain. 
Maybe this is a second breakthrough in the kessy world, because removing solved the short to the ground, and maybe it is possible to fix the doorhandle by replacing only the button inside the knob. 
I already disambled the knob, and try to get a new button, I think it is a standard button so I will go to the electrical store after my vacation. I'm already glad I fixed the batery drain, before I left. 

thanks Jorg


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## PanEuropean (Nov 3, 2001)

Jorg: 

Do provide pictures when you take the door handle apart - that would be new knowledge for all of us. 

Personally, I doubt that a shorted door handle would cause battery drain - I think that the KESSY is designed with a 'time-out' feature that causes it to disregard any signal (button press or touch of hand) from a door handle if the signal persists for an unduly long period of time. 

Michael


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## Jxander (Aug 5, 2008)

PanEuropean said:


> Jorg:
> 
> Do provide pictures when you take the door handle apart - that would be new knowledge for all of us.
> 
> ...


 I do not have Keyless entry in my Phaeton. However, I do have it in my Touareg. I had 2 door handles and the Kessy replaced due to problems similar to those experienced by Jorg - erratic behavior of keyless entry and battery drain in a short period of time. Replacing the offending door handles solved the battery drain. I believe a failed door handle can keep the keyless entry system awake for too long, if not until battery is drained. My Touareg was OK if I drove it daily but if it sat for a couple of days or more, I'd have to charge the battery before I could start. 

If a repair solution is also discovered for the door handle fix, that would be huge. Door handles are very expensive and come unpainted. I believe dealer price of a new door handle, painted and installed is about $800. Multiply that by 4 doors and add in a new Kessy and you're talking a major repair. 

Jim X


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## Jorgsphaeton (Sep 8, 2009)

tomorrow I try to replace the button inside the doorhandle, I bought one for 1 euro to give it a try, because the original one is a bit smaller, but good enough the give it a try, if it will fix the keyless close function then I will search for 4 (original) ones that will fit. so wish me luck.

I noticed the awake keyless acces function because the doorled (alarmled) stopped blinking after a minute, that doorled will notice you that there are problems with the alarmfunction.

picture will be posted soon

thanks
Jorg


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## Jorgsphaeton (Sep 8, 2009)

Just replaced the button in the doorhandle, but no results, the kessy doesn't reconize the new button. It could be that this not original button is not the same as the original one, or that it just doesn't make a connection to the circuit board inside the doorhandle. I can't solder it inside the doorhandle so I had to glue it on.
The VCDS shows no faults so that is ok, but it also shows that; when testing the button, it just doesn't show the testing field of that specific button, as it does on the other doorhandles.

What I think: I need the original button
or I have to fix some broken parts on the kessy itself because off the short to the ground by the moisture
or the doorhandle inside is ruined.

First I will try to get the correct buttons, that is the cheapest way, if that doen't solve the problem I have to discuss the kessy with Willem, maybe he got an idea to check the kessy.

other ideas are welcome

thanks

Jorg


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## nmour (Apr 19, 2013)

*KESSY module, driver side handles*

Hello everybody,

I also have issues with my KESSY unit in a '04 V10 Touareg. The driver side lock button and handle touch unlock do not work (both driver and rear left doors). The passenger side handles operate normally. The strange thing is that on the driver side, when I press the black lock button, I hear the relay clicking on the KESSY unit, exactly in the same manner as when I press it on the passenger side. However, locking does not work.

I replaced the two MOSFETs (one seemed to actually have source-gate leak), but nothing changed. I checked the 6 resistors, and they all appear to be correct (I measure between 0.2 and 0.4 Ohms, but I believe this is attributed to the accuracy of my DRM).

Would there be any ideas? Is there any chance the doors can be excluded via programming of the module, and the previous owner did something like that?

Thank you.

Best regards,
Nikos


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## Jorgsphaeton (Sep 8, 2009)

did you check the output behavior of the button in VCDS, I thought it is called 'output tests' or similar like that. I removed my button temporarely and in that test function the driver door button is not existing anymore. see above, still waiting to receive the correct buttons.

jorg


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## nmour (Apr 19, 2013)

Yes, I have, and the button is properly being reported whenever it is pressed. From all I can understand, it should lock the door. That's why I was thinking if it is possible to selectively disable certain doors at the dealer. If this is not possible, then there is definitely something wrong with my system, but if it is, it is a matter of visiting the dealer any paying them to recode it.


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## nmour (Apr 19, 2013)

I think that my problem is antenna related. I left my key on the driver side and tried pressing the lock button on the passenger door, and I had the same behaviour as I have on the driver side: the relay on the KESSY is triggered, but the car does not lock. When reading the unit with VAG-COM, various entries related to the antennae appear, but I figure they are not permanent, since if they were, I would not be able to lock/unlock any doors in a "keyless" manner. The fact that the report is not focused on one specific antenna, as well as that it seems a bit systematic that two doors on the same side stop working, makes me wonder if it is not actually an antenna or wiring issue, but rather a problem on another point on the KESSY. Would anyone happen to have an idea on that? 

Thanks, 
Nikos


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## StevenFT (Jan 26, 2012)

Nikos, 
I believe that the antennas need to be re-adapted after replacing the MOSFETs. If you're receiving open circuit fault codes on some (but not all) of the antennas, in particular R136, I suspect that there's a value stored in the KESSY related to the antenna that has become corrupted or no longer matches what the KESSY is currently measuring. 

I had my KESSY replaced approximately 6 months ago and had open circuit faults on two antennas that persisted afterwards. I replaced the antennas myself and extensively checked the wiring. After asking around in the VCDS forum, Jack from European Parts Emporium was able to give me some direction. See the end of this thread: 

Phaeton- new Start/Access (Kessy) module coding  

I don't know which adaptation channels in the KESSY controller need to be adapted. Detailed information on what goes on inside the KESSY is extremely hard to come by. I need to get my Phaeton to the dealer to have this performed to hopefully restore my keyless access functionality. 

Hope this helps, 
Steven


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## nmour (Apr 19, 2013)

Steven, 

Thank you very much for your reply, it was really informative. It is quite reassuring to think that it might be a coding/configuration issue rather than a physical failure requiring replacement of parts. I shall visit the dealer, since PIN is required for KESSY coding, and I shall post back with the results. I hope your issues get resolved too. 

Best regards, 
Nikos


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## Jorgsphaeton (Sep 8, 2009)

Just replaced the button with an original One unfortunately no result, problem is still the same. So I think the buttons of the doorhandles are ok but it could be a problem inside the doorhandle it self. I will investigate the controller later. I don't have vcds error coming up so that is pretty strange 

Jorg


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## WillemBal (Nov 20, 2010)

StevenFT said:


> ...I believe that the antennas need to be re-adapted after .....


 Hi Steven, 
This is odd. According to the repair manual, no antenna adaptation is after replacing an antenna or the KESSY. 

The text being used is: 

*No coding, basic setting or adaptation is necessary if.....(Antenna name and number) is replaced. Erase any DTC entries in DTC memory (via "Guided Fault Finding" etc.. * 

The applicable antenna's are: R136, R137, R138, R139 and R154. 
The authorisation antenna's in the door handles R134 and R135 are mentioned, but no specific procedure is referenced, other than "Install in reverse order of removal". 




Jorgsphaeton said:


> Just replaced the button with an original One unfortunately no result, problem is still the same. So I think the buttons of the doorhandles are ok but it could be a problem inside the doorhandle it self. I will investigate the controller later. I don't have vcds error coming up so that is pretty strange
> Jorg


 Jorden, 
You can check the door handle function via "Advanced Measurement Blocks" of the KESSY, using VCDS. 

Willem


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## Jorgsphaeton (Sep 8, 2009)

Yes I did that, but the driverside button isn't available there, this was the button with the shortcut. I removed the button to solve the shortcut and replaced it with a new one, but it is still not visible in VCDS. the other 2 are visible there but don't react on a button press, one of them also has a new button inside. SO I got two errors and both not visible with a scan. 
1. driverside button: shortcut and a new button replaced 
2. passengerside button: normal doorhandle problem with original button. 
3. passenger rear: normal doorhandle problem with new button inside. 
4. driverside rear: works perfectly. 

1 is an other problem then 2 and 3. 

I think I want to try to check the kessy. can you give me advice how the check the whole kessy? 

thanks 

Jorg


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## WillemBal (Nov 20, 2010)

Hi Jorg, 
I will check that, perhaps this afternoon. You need to have the key in your pocket when you press the button, but I'm not sure whether that affects the transmission of the "Button depressed" report in VCDS as well. I'll check that too. 
Regards, 
Willem


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## PhaetonV10-EST (Nov 5, 2011)

Hi

i have also been enjoying the battery drain and kessy not wotking as should, issue.
Today i took the kessy module out and i was rather suprised to see that that rubber gap under the module was missing!
So water has had free access to the footwell.

Anyway, the result of that looked like this:



















Hope that a local electronics shop can bring it back to life.


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## WillemBal (Nov 20, 2010)

PhaetonV10-EST said:


> Hope that a local electronics shop can bring it back to life.


Hello...first name  ,

It looks like only the bottom side of the electronics PCB was damaged a bit. Then there is a chance.
Ingress into the inside of the box is always possible due to a row of tiny holes in the socket. This row is a one of three, the other two rows are used for the connector pins and the third (bottom) row of pin holes has no pins. So no matter how well the box is sealed, water ingress is always possible via this row of pin holes.



> ...i was rather suprised to see that that rubber gap under the module was missing...


Are you referring to the red gasket surrounding the unit, or the gasket in the bottom of the car?

Willem


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## WillemBal (Nov 20, 2010)

*Gasket*

Coincidentally, I repaired my own KESSY yesterday because of the infamous antenna open circuit faults. Just the MOSFET's were replaced , the resistors which were fine (0.1 ohms all three parallel) 

It is interesting to note that one of the bottom plugs can be seen when the carpet is lifted. The big round one is visible just about 7 to 10 cm in front of the Kessy. I pressed this one from the bottom, to make sure that it moves up while pressing on it from the bottom.

So when this one is missing, water can freely penetrate into the cavity where the KESSY is mounted. This again proves that a regular inspection of the bottom plugs is absolutely necessary, in order to avoid water ingress.

Willem


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## WillemBal (Nov 20, 2010)

*Immobilizer faults*

I noted that since the time my KESSY became defective (about two month ago) it frequently occurred that the car would not start at once. Quite often, a message occurred in the instrument cluster, saying "Immobilizer activated", after a first attempt to start the engine using the start button.

The symptoms are that the engine starts for a second or so, then dies with the above message as final result. Switching off and on the ignition always resolved the issue. About one out of 3 times, this starting behaviour occurred.

With VCDS, the following errors are produced:

Address 01: Engine Labels: 07C-906-018-BAP1.lbl
Part No SW: 07C 906 018 B HW: 
Component: D1-6.0L-AT A ª5112 
Coding: 0000173
Shop #: WSC 01065 000 00000
VCID: 244DDB93E442E638643

2 Faults Found:
*17978 - Engine Start Blocked by Immobilizer 
P1570 - 008 - - Intermittent*
18331 - Please Check DTC Memory of ECU Number 2 
P1923 - 008 - 
Readiness: 0000 0000

-------------------------------------------------------------------------------
Address 05: Acc/Start Auth. Labels: 3D0-909-13x-05.lbl
Part No SW: 3D0 909 135 L HW: 5WK 470 22
Component: Kessy 6400 
Coding: 0213228
Shop #: WSC 01065 000 00000
VCID: 2E5939BBBA8E5C68827

Part No: XXXXXXXXXXX 
Component: ELV XXXX

6 Faults Found:
00179 - Access/Start Authorization Antenna; Drivers Side (R134) 
011 - Open Circuit - Intermittent
00180 - Access/Start Authorization Antenna; Passenger Side (R135) 
011 - Open Circuit - Intermittent
00181 - Access/Start Authorization Antenna (in Rear bumper) (R136) 
011 - Open Circuit - Intermittent
00182 - Luggage Compartment Access/Start Authorization Antenna (R137) 
011 - Open Circuit - Intermittent
00183 - Interior Access/Start Authorization Antenna 1 (R138) 
011 - Open Circuit - Intermittent
01299 - Diagnostic Interface for Data Bus (J533) 
005 - No or Incorrect Basic Setting / Adaptation - Intermittent

-------------------------------------------------------------------------------
Address 11: Engine II Labels: 07C-906-018-BAP2.lbl
Part No SW: 07C 906 018 B HW: 
Component: D1-6.0L-AT A ª5112 
Coding: 0000173
Shop #: WSC 01065 000 00000
VCID: 244DDB93E442E638643

1 Fault Found:
*17978 - Engine Start Blocked by Immobilizer 
P1570 - 008 - - Intermittent*

I have a feeling that this immobilizer problem is solved as well now. 
Willem


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## PhaetonV10-EST (Nov 5, 2011)

Hey Willem.

The bottom plug was missing. So water had free access.
Your described IMMO problem also occured sometimes, but not so often, maybe every 100 time.



Silver


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## Gridders (Mar 24, 2013)

*Kessy repair*

I can now report the second known successful repair thanks to this thread. I popped the module out having ordered the MOSFET chips mentioned and then took the lot by door to my local tv repair shop. An hour later it was all re-installed in the car and is working perfectly again. 

I did disconnect the battery having moved the seat and removed it. And had to start the car in the key first time for it to re-register presumably? All I need to do now is drive 50yds to teach the steering angle (ESP light is on and is quite normal after a power disconnect) and clear all the fault codes/ re-program the time and volume settings etc etc! 

Thanks to all you clever people for pointing me in the right direction. 

Gridders


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## PanEuropean (Nov 3, 2001)

The pictures below provide details of a good source of MOSFETs and resistors for Phaeton owners in Canada and the USA. Note that the prices are in Canadian dollars, as of summer 2013.

*MOSFETs and Resistors for the KESSY (Controller 05)
*


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## zenmoused (Nov 6, 2008)

Anyone have success reviving water damaged KESSYs? Mine was completely submerged (I drained probably 5 gallons of water out of the footwell). I dried the kessy out for several days and cleaned with isopropyl alcohol, however I'm getting the key symbol when i reinstall. No apparent sign of damage, going to borrow a good multimeter from a friend later today. I'm alright with soldering components (It's dead anyway) the only thing is I see everyone having success replacing the MOSFETs, whereas my board is completely blank in that region. Of interest as well, there was no rubber seal to my unit. I guess that's a feature VW decided to add later in production.











Brian


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## Paximus (Aug 26, 2011)

Hi Brian,

The usual problem with printed circuit boards and cable plugs, sockets, junctions etc that are submerged under water while powered up is that copper migrates through the slightly contaminated water from the areas at +12V to other regions connected to ground. So thin tracks and plug pins get thinner, or even disappear.

I can see there's still some corrosion in part of the top surface. That could be enough to disrupt some high-impedance circuit. Is the other side of the PCB all perfectly intact?

Chris


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## zenmoused (Nov 6, 2008)

Hi Chris,

Thanks for the reply. The back doesn't look too bad to my eye- I still have to borrow that multimeter so I can test it. 

Brian


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## Paximus (Aug 26, 2011)

Well, I hope you have some success. The reverse of the PCB has some interesting areas around the connector than could possibly do with re-soldering and cleaning, to help prevent signal voltages leaking across pins.

Chris


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## WillemBal (Nov 20, 2010)

Hi everyone,
I haven't been around for a while on the forum because another hobby of mine intensified since the beginning of last year. I have been hanging around Lelystad Airport many hours and days, being involved in purchasing a new type of light SEP aircraft and also to emerge some new business on the airport. Because it is the intention to extend this airport into a the Dutch government has well developed plans to extend the capacity of this airport in the near future, you can imagine that all the hours I spent on the airport are deducted from my Phaeton passion hours (although I incidentally met Wouter recently and then had a mini GTG on the airport)

I read the posts below of some fellow members who attempted to repair their Kessy by cleaning them using various methods.
First of all, I must say that I do not have an oughful lot of success with refurbishing drowned kessy's.

The general reason for not being able to repair the kessy is the fact that the damage is not caused during flooding with water, but during the drying process.
Usually the water entering the vehicle (i.e. via leaking bottom holes) is contaminated. The contamination is not only debris, but also smalller or larger quantities of salts, in particular remainings of the salting of the roads during winter time.
The water does not necessarily need to be contaminated a lot to cause damage in a later stage. During the drying process, the water evaporates causing the salt concentration to increase. After some time of drying, the remaining water/salt solution is saturated and then starts to crystallize. After complete evaporation of the water, the salt crystals remain on the board, causing leakage resistances. This is visible in the form of all those white area's around the solder spots.

Although the salt can be re-dissolved with water and can be removed, the major problem then is that a large quantity of problems are still there, yet invisible.
There are two major area's, one being the area formed by the contact surface of the big black connector and the PCB base and the other area is underneath the small (2 inch x 2 inch) metal cap.

The method of first drying and then cleaning with isopropylalcohol (IPA) or other alcohol therefore does not work. The only method that can be succesfull is to first drown the undried PCB in water and then rinse the PCB with concentrated IPA. The IPA dissolves the water and thus helps to remove it. During immersion in the water, a brush must be used to remove the salts. 
When the PCB shows salt marks as the photo's below (after cleaning with above method), then it is sure that the Kessy has been dried after drowning and therefore has been damaged irreversibly.

Although I was able to remove the metal cap on one Kessy (very difficult job) and even though I succeeded to make everything look "as new" (i.e. totally non-damaged), I concluded that it would be practically impossible to remove the big connector as well. This job requires de-soldering of the 30+ pins and the connector or the PCB would not survive all the necessary heat.

In addition, I am 100% convinced that leakage inside the black box is the result of the row of unused pin-holes. After penetration via these pinholes, salt residues are first formed between the used pinholes of the same connector. Because these residues cannot be removed, the problem will persist despite all good intentions and skills.

I hope this may save some desillusion after a lot of good work! 

Willem


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## Paximus (Aug 26, 2011)

Hi Willem,

Welcome back, with your interesting news, I'm glad your 'forum time off' was for excellent reasons!

Thanks for the helpful comments on PCBs. It sounds like _Hope _will not overcome _Adversity_, in this case.

Chris


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## derek2 (2 mo ago)

I accedently destroy the SMD Capacitor between the two MOSFETs. Can someone please tell me the value of this capacitor or alternative I can use?


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