Volkswagen Repair: 2006 New Beetle alarm problem., new beetle convertible, door latch

Question
QUESTION: After a heavy rain, the alarm on my 2006 New Beetle convertible goes off intermittently, with no rhyme or reason.  It doesn’t last long (less than 30 seconds)—it either goes back off by itself, or I get to it quickly and hit the unlock button on my key to stop it.  It will continue to do this for up to a week and a half after the rain.  No water in the car or trunk that I can see.  I did have the instrument cluster replaced soon after I bought the car in 2006 due to it not starting in cold weather.  The alarm problem started about a month ago, and the dealer had the car for a week.  They couldn’t duplicate the problem, and none of their diagnostics showed anything wrong.  My neighbors are going to kill me if it doesn’t stop going off at all hours of the night, and there's no end in site to the rain here.  The dealer is stumped.  Any ideas?  Thanks, Chrissy

ANSWER: Hi Chrissy;

This sounds like a door latch problem to me.  Do all of the lights in the interior come on when the drivers door is opened?  Do the windows come down as the unlock button is pressed?  Have the windows ever gotten stuck, or had the "pinch" feature send them down for no apparent reason?

Help me with the answers to these questions, and I'll help you some more too.

Thanks.

---------- FOLLOW-UP ----------

QUESTION: Yes, the lights come on and the windows go down like they are supposed to.  However, the "pinch" feature did send them down sometimes.  I mentioned it to the dealer when it was in for the alarm problem, and when I picked it up they said it was due to dirt/debris in the track, so they lubed it.  Haven't had the window problem since, but didn't have it much before that, either.

Answer
Thank you Chrissy;
There is one other thing that it could be then, and that is related to the window motor itself.  There is a "comfort module" in the drivers door that talks to a lot of other modules in the car, and if it thinks something is happening, that is actually NOT happening, it can set off the alarm.
Unfortunately for all of us it is a little more difficult to diagnose because of 2 things.  There are no door lock rods, with little buttons that pop up, or go down when the doors on a Beetle Convertible are locked, or unlocked...so you can't watch for their operation...sort of a limitation, and then there is another difficulty, and that is the VAS 5052, or VAS 5051B scan tools have to be used to communicate with car, and start asking it some questions for a change.

So, I think this.  The comfort module needs to be selected with the scan tool, and then "measuring block values" need to be investigated.  This could take some time for anyone, and even the best, fastest tech. won't like doing it, because VW doesn't pay for diagnosis, just repair, on warranty.  It will be necessary to go into "Guided Fault Finding" first just to get the proper paper trail started at the dealer, and then the tech. might get paid for some of the diagnosis time.

Anyway, in conclusion, there is one other thing that I'm reminded of, and that is this..."coding."  All of the switches, and sensors have to have the same coding ...ie., to that car, if they don't the alarm will go off without warning.

I realize that most of what I've said here is "mumbo-jumbo" but with the advent of CAN bus technology in Volkswagens, Audis, and other European cars, the "CAN" computer area network needs to be able to communicate with all of the other little computers in the car in a special way, and if a sensor, or a switch isn't "coded" properly when combined with the other switches, and sensors then that is where the troubles begin, and without factory training, and factory equipment, a technician is going to be unable to repair the customers' car.

I hope you have a good local dealer who will help you, Chrissy.  Good luck.  Thanks for your patience.

Hello, again Chrissy;

Thank you for your kind feedback.  I hardly deserve it.  I forgot about something, and feel that I should bring it to your attention.  The system that keeps someone with a matching key from stealing your car is called the "Immobilizer."  The 2006 model year is the first year for the "Immobilizer IV."  Not that that means anything to you, but the Immob. 4 is unique, and different from the previous generations from 1999 through 2005, and it just occurred to me to ask another question of you, because it may be something significant.  Did you buy your car new, or used?  Also, did you recently have a key made, and "coded" to your car?  Or, for that matter, did the dealer, for whatever reason?  The funny thing about this is, a 2006 model year key, part number is different by only 1 digit, or letter, and in as much as they look identical, can be cut identically, and then coded to the immobilizer, even though they are intended for a different series, or generation of electronic part.  The reason this struck me, and made me write a follow up is because I remembered that you said in your earlier question that the instrument cluster has been changed.  The immobilizer had to be "re-coded" at that time too...to the new instrument cluster.  Please forgive me for rambling on, but it might be important to remind your local dealer that this occurred.  Your car happened to be one of the ones that required the updated cluster.  I never found out why this had to take place, but feel that there was something about the new generation "Immobilizer IV" that necessitated the change, and that seems the logical culprit behind your alarms' questionable behavior.