Probably just an open connector where Ford may have plugged something else in on different applications.
Capacitors or condensors are common on voltage regulators. Yes, it could be an used connector too. 24riverview is probably right because you'd expect to see the symbol for a capacitor.
Funny, I was gonna post to disregard my answer and listen to you. Worked on Ford dump trucks for years and they all had them. I say it's either the condenser/capacitor or the connector for it.
The only tester I know would be a full-fielder tool. It plugs into the regulator connector and rules out the regulator as the culprit in a charging system problem. But not just one ckt. The capacitor's job has changed over the years. Early on it protected the points inside the regulator from arcing just like the condensor in a dist. protects points. Then it helped protect solid state devices from voltage spikes. Devices like early electronic ignition modules and solid state voltage regulators. Now capacitors, diodes and resistors (sometimes called self-commutating) keep voltage spikes out of computers. BTW in this case capacitor=condenser. But in no other case.
Yep. That's not any recognized symbol for any component that I know of. Ill enter a guess of connector, but it should have a number.
My old Hudson Superjet wiring diagram has one like that. It is just a spare connector. I believe they were put for under the hood lights.