On an '81 vanagon alternator there are 3 connections that the wiring hooks
up to.  On one side it says D+ and on the other it says B+.  I assume that
shows that one connection goes to the battery and the other to the
alternator light in the circuit board, but what is the other (middle)
connection for?  I'm installing an isolator but the directions don't say
anything about a third connection (unless it also goes to the battery).
Does anyone know anything about alternator connections.

Thanks for you help,
Danny
'81 Westy