I have the same problem - only that if I try to lock the van from *any* door,
the locks will lock - then unlock.

The manual does not address the central locking system at all, so my sence is
it is a "replace the parts" until you find the right one.

I hate having to manually lock the doors because on my van, all the doors must
be locked with the key.

Budd Premack wrote:

> My 87 Wolfsburg has a locking (non-locking?) problem.
>
> When the driver's side power door lock is engaged (*) (either by key or
> button), the passenger door does not respond, but the sliding and rear door
> locks continuously cycle on and off.  The cycling will stop only if the
> passenger door is manually engaged.
> (*Engaged means taking some action, either locked or unlocked.)
>
> That is, if the two front doors are both locked or both unlocked, no
> problem.  But if only one of the front doors is locked, and the other is
> unlocked, chaos reigns.
>
> For a while the problem was in suspension, as long as I ONLY used the lock
> on the driver's door.  However, my son unwittingly unlocked the sliding
> door, and now I cannot go back to the former suspended mode, no matter what
> combination of locking/unlocking I try.
>
> So now I have to either manually lock both front doors (which also locks
> the sliding and rear doors) or manually unlock both front doors (which,
> naturally, unlocks the sliding and rear doors also).
>
> I have researched the archives and found several references to this
> problem, but the only solution seemed to be disabling the system, which I
> would prefer to avoid.
>
> Is the relacement of the passenger door lock motor the probable cure, or is
> there some other likely culprit?
>
> Budd Premack
> 87 Wolfsburg, 84 Vanagon,  86 Syncro
> 73 Super, 64 Bug
> Minneapolis, MN