Could not find anything on this, so here goes:

My 1998 A4 Quattro has a curious quirk - one or two seconds after I open the trunk with the key, all of the windows in the car go down. Somewhat inconvenient when it's raining. Anyone know of a fix?

 

So when you turn the key in the trunk lock, how long are you holding it? One of the convenience features on these cars is the ability to roll the windows up and down by holding the key in the lock/unlock position. Could be you're just inadvertently activating that feature?

 

^ I'm just guessing, but i dont think the lock cylinder on the trunk is linked to the window feature that you can utilize by holding the key locked/unlocked in the driver's door lock cylinder. But hey, i've been wrong before...

 

Does it happen when you unlock using the trunk key, without actually opening the trunk? Or does it happen when you simply open the trunk? Or the combination of both? The trunk switch is a ground signal, as is the signal to unlock the car (or roll down the windows), so they could be shorting together either internally or externally of your central locking module.

 

No, it does not seem to be related to the lock per se. the windows open when I push the button to open the trunk, and it is intermittent. Lately, the driver's door lock will not unlock the car, and I have to unlock the car with the trunk lock.

 

My money is either on a damaged harness right near the central locking module, but more likely some internal failure/short of the central locking module.. Im thinking this is likely the case based on the fact that you have other issues unlocking the door from the driver side. The central locking module is located in the rear most right side of your drunk behind the carpeting.