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