Hi there I m new to the forum Michel is the name and I m from the Netherlands Restoring a Dodge Dart 1965

New cars are wired differently than old cars and trucks.
The wiring diagram in the Plymouth or Dodge Chassis Service Manual is pretty complete and accurate - although some years better than others.
www.mymopar.com has a digitial copies for '66 which you can download.

Yes a single circuit can have a several device on it. This simplified the wiring layout and construction of the harness.

https://www.forabodiesonly.com/mopar/threads/wiring-diagram-codes.507628/post-1973726553