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We own a 2003 Passat that at any given time, all four windows will go down by themselves or when you put the key in the ignition, there will be a loud beeping noise. Totally clueless on this one. Thanks in advance!!
 

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Any lights on the dash or message in the display when it beeps? Pull up the carpet on the driver side and pull out the plastic case under the driver seat area. It is the Comfort Control Module (CCM). It may have gotten wet and be malfunctioning due to water and/or corrosion.

The beeps may be an ABS module issue.
 

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Discussion Starter #3
Thanks, sir! I will check and see what's going on. Any clue why all four windows will decide to roll down on their own? That's really the bigger issue. This is my 17 year old daughter's car and she goes into a panic about the simplest of things.
 

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As VAGguy suggests, you'll need to pull up the carpet and check the CCM for evidence of water or wetness and or corroded wires. The CCM is the module that controls window functions.
I have a 98 GLS that had a similar problem, window would go up or down at random while driving. My particular issue was a malfunctioning window motor inside the door.
Seeing as you have all four windows that are effected, that points to the CCM.
 

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All four windows going down together is a function initiated by the door key switch (hold key a second in the unlock position). Evidently the CCM is getting that signal, either due to a fault at the switch, or the CCM itself. Do all doors lock/unlock normally normally when using the key?
 

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I started having trouble like this, and there was a bunch of other stuff too. The problem (and mine was a w8 so will be different) was water ingress into the rear control unit for my fuel. It was shorting out, and the result was to pull all of the other computers down making a bunch of naughty stuff happen totally unrelated to the actual fault.

There is a function that can be enabled/disabled that puts all your windows up if you have closed your doors by turning the key in the door. That sounds like it is happening for no reason.

Definately check for water ingress in the modules on the floor-pan of the vehicle. VW is not the best for placement.
 

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A wet CCM (comfort control module) is certainly a possibility, but I'm with ylwagon (post #5) on this one. If you put the key in the driver's door, then turn and hold, the doors will lock/unlock, then after a brief delay the windows all roll up/down. Really cool feature on a hot day, or if the kids left half the windows down. There are microswitches in the driver's door latch assembly that make this happen--try out this function; it might lead you to the root cause.

This is a networked system, which is why some malfunctions seem very odd. Each window motor has a CANbus node in it which communicates to the CCM. Virtually everything on the door, including the door latch module, wires to the window motor. From there, all the control and status signals travel as data on the CANbus--there are relatively few wires that cross the door hinge (power, CANbus, and audio, mostly).

If the floor has been really wet, the CCM and/or the wires will be damaged. Usually things get flaky, or quit working altogether. There are many splices in the wiring harness under the driver's floor mat; some were poorly sealed (at the harness factory), so even a little moisture would be troublesome.

Back to the door--there were many issues with the door latch modules, often cracked solder joints, although one of mine had a broken part. As such, there are lots of DIYs on getting them out. At the same time, be very cautious of used ones, and avoid cheap ones like the plague (lest you find your door stuck shut...). My first time was about 3 hours getting a door latch module out and back in.
 

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to piggyback on the water ingress , there is a ground terminal just a little forward and to left of CCM (ground wire from this) that gets severely exposed a corrosive environment
 

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Referring back to the third post, you stated this is a car for your 17 y/o daughter, who goes into a panic over simple things. This type of person driving a B5 Passat will end in one of four ways after the 20th thing goes wrong.

She will spontaneously combust, or She will finally calm down in resignation, or

You will get her a different car (Like a Honda), or
You will spontaneously combust.
 
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