Steve Savage submitted this article to RVtravel.com when he was a Master Certified RV Technician with Mobility RV Service.
There are several common mistakes that often pop up when folks attempt to replace their plugs and receptacles that power their trailer lights and brakes.
The first mistake is pulling a wiring diagram off the Internet that designates wire colors. Owners often assume the colors on the diagram will match the wires on their truck or camper. You need to remember colors are irrelevant. What the wires do is important, not what color they are.
Anytime wires have been removed or come loose and left hanging, the prudent next step is to determine the function of each wire and write it down, then fasten the appropriate wire to the correct pin on the seven pin or cord. That way any arrangement can be wired to any plug.
The second common mistake we often see is that of forgetting to take note of the orientation of the wiring diagram that is being used. Sometimes the wiring diagram shows the receptacle from the back, sometimes from the front. Get confused and you will quickly discover things do not work right. The most common symptom is many lights going on at once when power is fed through the pin that should be the trailer ground.
If what you’ve just read makes sense to you, then go ahead and proceed with your own wiring. In the event it does not, I would suggest you are working over your head and would benefit by hiring someone to install your components, or ask a more experienced friend for help.