From the bloggers at Outside Interests.
Most people don’t think about the fat black cable that connects the Airstream to the tow vehicle—until something doesn’t work, like taillights or brakes.
It’s called either the “umbilical” or “7-way” cable, and keeping it in good condition is important because it’s the critical link for correct operation of trailer brakes, lights, and signals.
Since 1989 all Airstreams have used the same wiring arrangement. Each location in the 7-way plug is dedicated to a specific signal.
To read the full story by Outside Interests, click here.