Like Terry said, it is a 12V accessory socket.  Others have mentioned that
BMW motorcycles still use the same type of socket and their dealers have
parts for them.

Mike Snow

>
> Hi all,
>  82 Westy diesel has a silver thing to the left of the heater
> controls about the size of a dime.
> Looks like a light bulb socket. It is not the coldstart knob,that
> is 1 inch down and to the right.
> I put a test light up to it and it is hot....12v with the
> ignition off. I initially thought it was a dealer
> installed indicator for water in the full. My other diesel
> vanagon (van-not Westy) did not have
> the similiar thingy. However I looked a another Diesel Westy for
> sale and it had the same darn
> silver thingy.
> HELP ME
> gatorxray@netzero.com
> mike
>