Pictured below is the 7 way connector, which is the connector style in most common use on RV trailers and is becoming increasingly popular on horse and utility trailers.
As you can see in the illustration below the back side of the connector body is labeled at each terminal. The labels are listed below with the function assigned to that pin.
On the tow vehicle side wire color alone should not be relied on, always test and match the function to the appropriate terminal.
On the trailer side RV's for the most part are wired to match the connector colors. Any plug that has been changed or extended, along with utility trailers should be tested when replacing for any reason to be sure the function matches the terminal.
It should be noted below that the center terminal is labeled as an auxiliary circuit, most commonly used for backup lights not a ground terminal as many try to make it.
If you are trying to wire a car/truck that has separate turn and brake lights to a trailer where they are one piece you are going to need an Converter. These use diodes to change the currents to the tail lights. They look like this (CONVERTER) and are sold at most parts stores for around 10-20 bucksFor a list of dealers who can service your trailer brakes, or find a location of a dealer who carries parts for your particular trailer, visit our website