Are you sure its not engaging when driven? Sometimes it takes a while
to engage. You've got to get the front and rear to turn at a different
rate - like going into a corner.

If the pin in the tranny is free and the actuator is moving in and out
(which means you have proper vacuum) then it should engage with a
little corner-turning.

Someone else will have to chime in regarding the light circuit. I
assume the circuit gets closed (light goes on) when the actuator is
moved forward, but not until full engagement I would think.

Jeff

On Oct 12, 2009, at 10:06 AM, Automatic digest processor wrote:

> Date:    Mon, 12 Oct 2009 09:55:42 -0700
> From:    Bruce Todd <beeceetee@GMAIL.COM>
> Subject: diff lock woes
>
> Okay - not to stretch this email into a long winded tale...I had my
> motor
> out of my 86 syncro westy this past summer to have a number of repairs
> completed.  The main repair was to have the head gaskets replaced as
> I was
> having overheating issues.  With the motor out, it was checked
> thoroughly
> for wear and then the top end was partially rebuilt.  At the same
> time I
> replaced brake-lines, ps lines, ps pump, gas tank straps, coolant
> hoses,
> fuel lines and a few other odds and ends.  I now have a stronger
> running
> motor that doesn't leak coolant or oil and idles very nicely.  I
> also feel
> relatively more confident when taking my young family on longer trips.
>
> Since buying the van several years ago, the rear diff lock has
> always been
> seized.  Here was my opportunity to get this fixed with everything
> else when
> the motor was removed.  The mechanic unseized the locking pin and
> put it all
> back together telling me that it took minimal pressure to engage the
> lock.
> This was all theoretical as when it came time to road test - the
> diff lock
> wouldn't engage.  The mechanic told me to return when his shop was
> less busy
> and he would work on it some more.  What does work is the green
> indicator
> dash light which permanently stays on once the vehicle starts
> whether the
> diff is locked or unlocked.
>
> Twice I've taken off the actuator to check whether it works when I
> engage
> the dash knob and it does.  Pulling out the knob elongates the stem of
> the actuator...pushing the knob in, contracts the stem.  The diff
> lock has
> worked with the van on a hoist with the tires off the ground slowly
> being
> rotated and the locking pin being pushed with the actuator and with
> the help
> of a pry bar.
>
> Yesterday I crawled under the van to unplug the wires which connect to
> indicator light switch - which is located above the actuator.  Even
> with
> the plug disconnected the green dash light was still on.  Does this
> mean
> that the diff lock pin is partially engaged or is there something else
> occuring?  Why would the light stay on if the plug is disconnected?
>
> This pretty much is the last thing that doesn't work on my van - and
> I'd
> love to get it working.  Any words of wisdom would be most
> appreciated.
>
> Thanks
>
> BT