The 7 pin trailer plug is used on recreational trailers and vehicles. After a long time these connectors may become corroded and may cause the wiring problems, or may also become damaged and hence will require a replacement. All these parts can also be bought online. Various trailer wiring connectors are available that range from four to seven pins and allow power transfer for the purpose of lighting besides auxiliary functions like the electric trailer brake controllers, a 12V power supply, or backup lights for interior trailer lights or a winch. You should choose only that connector that has the requisite number of pins for the particular functions of your trailer. The connectors that are available are 4-Way Connectors, 5-Way Connectors, 6-Way Connectors, 7-Way Connectors, etc.
An electric device that is used for supplying the tow vehicle's power to the electric brakes of the trailer is called as an electric trailer brake controller. These devices are available in many styles and are differing in their looks to several brakes powered. There are two main groups in which electric trailer brake controllers have been separated and these are time delayed or proportional.
The trailer wiring harness connection should be made to the signaling system of the automobile. You may have requirement of seven, six, five or four prong pins by the interface of the electrical circuit that depends upon the trailer's size and type. One of the ways that is quite common for connecting a trailer to the signaling system of the automobile is by using a four pin (or four wire) electrical harness. More details on the trailer wiring harness can be obtained with the help of internet. If the proper trailer wiring harness system is not used then the turn signals and brake lights may not work properly.