1975 Ambassador - running lights / brakes

[wvmstr]

I have used my Airstream as an office, the trailer never moved once I set it in place to be my office 10 years ago.

Now I am in process of making it ready for sale. So far I have brake lights, backup lights and blinkers working. Looking for some insights on wire routing.

This trailer has a male connector underneath the front window. Inside I have the cover removed so I can look at the rear of the connector.

The green wire is for the running lights (and tail lights I assume).

The large yellow wire is for the brakes.

The white wire is ground.

The users manual shows a cylindrical item called "Sway Control Running Lights" between yellow and white. Where is this item? Underneath or inside?

What is the general routing of these 3 wires?

Thanks in advance.