Curious fault developed at the weekend. As you drive along the interior lights slowly pulse (slowly coming on and fading off, not flashing) on and off. I have had a problem with the nearside passenger door not shutting properly for a few months. Initially it needed a bit of a slam but now a strong pull closed sits it home and the "open door" indicator on the DIS goes out. Not sure if the 2 are connected. Any ideas what this could be? Car is 2001 2.5TDI quattro Avant.