The electric door locking system on my van has for 2 years functioned properly on the passenger side, but mechanical locking only on the driver door.  Recently, it failed completely.
I took off both door panels and suspecting broken wires in the driver side harness which had obviously been worked on by PO, undid many layers of electricians' tape. I found the red wire giving power to the lock motor broken, and a brown ground wire broken(the ground wire was not the one from the lock motor.) These are now repaired.
See: http://community.webshots.com/myphotos?action=viewAllPhotos&albumID=552277097&security=awgQlF  for some pictures.
(I'll try to use tiny URL next time)
So, here's the situation:
1) When everything is hooked up, all the locks(driver, passenger, sliding door and hatch lock) all lock - and promptly unlock.
2) When I unhook the power on the passenger door, it of course has to be locked manually. But,  locking the driver side electrically, the driver, sliding door and hatch lock and stay locked.
3)Unhooking power to the driver door kills all the power including the passenger door - everything is on manual.

I pulled the passenger door motor apart and found a broken spring(see pictures).  By stretching the big part of the broken spring the electric contacts needed are maintained.

So, the big question, where do I look for the problem now?  I needed the van, so everything is closed up, but I would like to resolve this for a lengthy trip planned in August.
In the archives there is a post of doors unlocking and promptly locking again.  I don't know how that problem was resolved.

Ed Wiebe
1990 Westfalia