I'm hoping I phrase this properly. I have an 84 Vanagon, 1.9
I bought it running very poorly,  exhaust hanging off it, etc etc

over the last month or so, I have rebuilt the exhaust, plugged in every hose
and
switch, with the exeption of one.  There is a yellow connector (two slots in
it) hanging out of the
wiring harness,  on the right side of the motor,(if you are standing there
working on it)
its low down the side of the engine ,  it only comes out of the harness
about 3 inches, and its below the airfilter.
There is nothing close to it that I can see to connect it to.   After hours
of pouring thru
the bently manual, I deduced that the square plastic switches that ride next
to the throttle
body, and clearly shown in the Bently guide are missing.  That didnt help me
with the wire.
There is no way that the wire that i have hanging could reach that far.
Then,  after looking
for the hundredth time at the image in the Bently manual, I see a reference
for later in the model year
versions that were produced with a single switch. That switch is at the very
bottom of the throttle body
and looks like a flat washer with a lead coming off of it.  Im guessing that
the guy I bought my vanagon from
removed it, or, maybe in working on the throttle body at one time, just
didnt see a need to replace it.

If there is a way to tell from the serial number of my vanagon whether it
was built late enough in the model year
that It may incorporate that one switch setup, and you can help me tell, it
would maybe send me in the right
direction.  The serial number is VW2YB0253EH023109

The old girl is running much better, Timed a little better, idles a little
better, has a bit more power, but the gas milage
sucks. 12 maybe. I'm thinking this switch has something to do with it.