It is the crancase vent heater/restrictor. It prevents water vapor from
freezing and blocking off the vent. It gets 12 volts when the engine ie
running. It is feed from a 5 amp fuse located in the black splice box,
front left of the engine compartment.

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf
Of Claudio Cella
Sent: Sunday, January 05, 2003 1:08 PM
To: vanagon@GERRY.VANAGON.COM
Subject: unknown switch?

Good morning Volks, once again i need to tap this well of knowledge.  I
am in the proces of replacing fuel lines (thank you for all your help on
that as well) and have removed all of the intake "spider" plumbing.
I will try and describe what i am looking at and where it is located on
the vehicle - i am hoping someone can tell me what it is and what it
does.
It is located (and joins 2 rubber hoses) on top of the engine, just
beneath the idle stabilizer control valve and slightly to the right.
Connects from the cylindrical black tower (about 8" high and 4"diameter)
located on top of engine at rear where the cases join, and runs to the
intake plenum.
The switch itself is just a hollow plastic cylinder about 3 to 4" long
with a portion of its inner wall lined with copper.  There is a
electrical connection on this item as well.  The hoses connect at either
end of this item and seem to be rotted, in fact the portion closer to
the "black tower" is collapsed/crushed to less than 1/4 of it's inteded
size.  The hose with switch is used to recirculate crankcase fumes back
to the intake and combustion chambers.
What does this item do??
Forgive my rambling above - as i read it i wonder how you folks will be
able to understand all the mumble jumble.
thanks very much.
87  Vanagon GL  7 pass - 2.1
90  Jetta  TD