Trailer light converter

A Trailer light converter is an electrical component used for connecting the wiring of a trailer onto a towing vehicle. It is sometimes necessary because of the legal requirement for trailer lighting. Furthermore, from a technical perspective, it is used for wiring the two vehicles together to power and synchronize their lighting systems. A trailer light converter assists in adapting the differences in voltage and the number of wires. 
Most basic trailers in Canada and USA usually have only one light (with one wire) on each side that functions as both a turn signal and a brake light (though sometimes there is a separate yellow and red light for signal and brake lighting). The brake signal from the towing vehicle usually needs to be received by the converter and then sent to both the left and right trailer lights.
Wiring.
Trailer light converters generally follow a 4 wire electrical color scheme. (See Table 1)
The "Towpower" Trailer light converter, as portrayed on the right, follows a five colored wire electrical scheme.
"Towpower" is manufactured by "Reese" and hold various patents for trailer light converters.
The other end of this device uses a 4-Way flat wire connection.
Trailer light wiring options.
Depending on the towing equipment of a vehicle, there are possible installation variants: 