Every trailer connector carries a number before the word pole. This designation refers to the number of wires. A 4 pole trailer connector is suitable for four wires; right and left turn signals that include the brake light, running lights and ground wire. This represents the basic number of wires and lights needed for a trailer. Connectors with higher numbers offer more options for wiring, such as back up lights and electric brake control.
The 4 pole trailer connector utilizes four color wires. The green wire is the right brake light and turn signal while the yellow wire represents the left brake light and turn signal. The ground wire is white. The final wire is brown and connects to the running lights, which are the side markers, the taillight and license plate light. The suggested wire gauge for all wires except the ground is 18. For the ground you can use a 16 gauge wire.
Each trailer has a certain number of pins. The pins represent the number of functions needed to operate the trailer. For the ground wire there is an uncovered pin in the towing vehicle and a covered pin in the trailer. The brown running lights wire attaches to the first covered pin in the towing vehicle and the first uncovered pin in the trailer. The left turn signal wire fits the second pin, and the right turn signal wire finishes the connection with the third pin.
The green wire attaches to the right turn of the towing vehicle's wiring harness and the right turn signal of the trailer. The yellow wire goes to the left turn of the towing vehicle's wiring harness and the left turn signal of the trailer. The white ground wire attaches to a ground point on the vehicle and trailer. The brown wire attaches to the towing vehicle's taillight wiring harness and then to the taillight of the trailer.
