To connect the electric system of your trailer to the vehicle you will be using special connector. Connecting the wrong color wires will result in mismatched taillight functions and confusion on the road.

Al 4319 Wiring Of 7 Way Blade To 6 Pin Round Also Wiring
Standard 6 pin trailer wiring. Back up lights 7 pin connector. Expanded use trailer with brakes aux power amp. The 5 pin has a design and pin layout that is identical to the 7 pin iso 1724 connector with the exception for the lack of pin 1 l and pin 4 r. 6 pin connectors also exist but they are less common 1 4 wire the first 4 pins just like above and the 5th line goes to the brakes. If you have a trailer with a lot of lights the diode and relay wiring is preferred but if you have a trailer with a simple light arrangement it is usually sufficient to wire to 58l. This connector is sometimes present on vintage vehicles and the actual wiring may be completely different from what the standard states which means that measuring before connecting is a good idea.
There is a suggested and common method for 6 function trailer wiring. Right turn left turn ground tailmarker brake battery. Allowing the tow vehicle to control the trailers lighting system. Standard 4 pole wiring harness for use with vehicles that have adequate power and standard wiring system these simply connect into existing wires on the vehicle and have a 4 pole flat connector to attach a trailer. You will have the following functions. I have included a help article on trailer wiring that includes a diagram and wiring matrix that explains wire color function and gauge needed among other helpful information.
Use this 4 pin trailer wiring diagram to properly wire your 4 wire trailer plug. To abide with state laws trailers must be equipped with the proper brake and tail lights and the trailer connector wiring adapter allows you to connect your vehicles electrical network. Following the standard method for wiring a trailer connector is vital to the safety of your vehicle while towing. To ensure your trailer has safe visible and legal lighting a trailer connector wiring adapter may be a necessary towing accessory. By law trailer lighting must be connected into the tow vehicles wiring system to provide trailer running lights turn signals and brake lights. Some vehicles send only one signal per wire.
Trailer electrical connectors come in a variety of shapes and sizes. Above we have describes the main types of trailer wiring diagrams. Converter for use with vehicles that have separate turn and brake light wires. Below is the generic schematic of how the wiring goes. 4 pin trailer wiring diagram. The basic purpose remains the same whether your truck and trailer is using a 4 way 5 way 6 way or 7 way connector.
In market there are many special converters 1 2 3 that solves the problem of connecting a car with european wiring to a trailer with north american wiring. Blue electric brakes or hydraulic reverse disable see blue wire notes below 6.