Okay, I have a mid-1950s freight engine 4-4-2 with five wires running from tender to engine, four in the standard configuration using the four pin connector, but a fifth wire, black, lying loose, coming from the tender, wishing to be connected to something, but I have no idea what. Anyone have any ideas what this fifth wire is about?
On the engines I’ve seen with this configuration, the wire ends in a single pin, and plugs into a socket above the standard four pin socket.
I believe this wire provides power to the smoke unit and lightbulb independent of the motor, so that they will continue to work while the engine is in neutral.
Also, Portline Hobbies’ website has wiring diagrams for various AF engines, both steam and diesel. The website is portlines.com. They also have a fairly extensive ‘how to repair’ section.
Bill
Thank you for your help! All I could imagine was some kind of grounding wire, but this makes much more sense.