Wiring a Trailer and Plug
There are several types of plugs / sockets for your plant trailer and vehicle on the market.
The most common of them is a 7 pin round or 7 pin flat.
Some newer vehicles are now incorporating a 12 pin flat for more options on power to trailers.
Below are the diagrams for wiring standards and common plugs on the market.
In spite of continued improvements in alloy trailer wiring and electrical components, wiring problems can occur if regular maintenance is avoided. Many of the problems we see with a trailers electrical system stem from the conditions under which many trailers are operating in. Under gravel road conditions the underside of the trailer is being bombarded by an abrasive mixture of sand and stone (gravel). The trailer is literally being sandblasted. This sandblasting effect can damage the wiring underneath the trailer. The most common problems are with the electrical wires coming out of the electric brakes. It is important to inspect the wiring on a regular basis.
Other causes of wiring problems are poor grounding or poor contacts in the truck end or trailer end electrical plugs. Often there is corrosion on the electrical plug terminals and that prevents proper electrical conduction. It is a good idea to spray the electrical plugs with a good penetrating fluid or WD-40 to help dissolve the built up corrosion. Don’t forget to check the electrical ground as part of your check list if your trailers electrical system is not working properly.