it requires vacuum to unlock.
it's not spring loaded to 'unlock' .

if the hoses are reveresed on the actuator,
I think you'd just have reverse logic at the dash knob..
like in to lock, out to unlock .

remove the actuator, ( not always easy ) and operate the shaft for the
lock mechanism manually ..
see if it moves like it should.

On 4/18/2012 1:56 PM, craig cowan wrote:
> This is a problem...
> Today I was working on fixing the driveline vibration and finally got
> around to hopefully fixing the diff lock. The diff lock has never worked
> since I got this van, but when I had the transmission out tested it with a
> hand vaccuum pump and it locked well.
> I was missing a short piece of hose from the "main hose" that runs along
> the frame rail to the blue check valve going into the "Balls". I installed
> a piece of hose. Without turning the diff lock knob or anything, the
> transmission locked when I started the engine and a few attempts at driving
> (about twenty feet) confirmed that it's definately locked. I don't want to
> drive it again and damage anything, and I want to get it disengaged, even
> if i can't get it "working" to relock.
>
> I took the check valve off just to relieve the vaccuum and sure enough, it
> hissed upon release. This seemed like it should have fixed it, but alas,
> still locked. Does it require vaccuum to "UNLOCK" or just to lock and lack
> of vaccuum unlocks it?
>
> Perhaps my hoses are just swaped at the lock actuator?
>
> -Craig
> '87 Sunroof Syncro
>