Basically it is another 12v circuit typically used for a reverse light reverse lockout for trailer brakes. There is a suggested and common method for 6 function trailer wiring.

7 Way Trailer Plug Wiring Diagram Plug To Vehicle From H1
6 way trailer plug wiring. 6 way wiring is most common on gooseneck trailers and allows for use with a brake controller. Hardwire 4 pole trailer connector kit for vehicles with combined wiring where the turn and brake signals are sent along the same wirequick splice connectors and circuit tester included. 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. Provides a 4 way flat trailer connector at the back of your vehicle to power your trailers signal lights compatible with 5 pole 6 pole and 7 pole adapters sold separately connects. If there is no. By law trailer lighting must be connected into the tow vehicles wiring system to provide trailer running lights turn signals and brake lights.
The black sometimes red 12v and blue electric brakes wire may need to be reversed to suit the trailer. Gander flight 4780 views. For long lasting use and a reliable connection the housing of this 4 pin trailer wiring connector is made from durable black plastic reliable connection. 6 pin trailer wiring introduces two new functions a wire for connecting trailer brakes and a wire for 12 volt auxiliary power. Pop up camper wiring harness downgrade converting 7 way rv trailer plug to 4 way flat duration. Versatile design this trailer wiring connector makes a great replacement 6 way wiring plug it matches industry standard 6 way round connectors and is commonly used for towing horse trailers farm trailers boat trailers and utility trailers it can be used to connect the taillights brake lights turn signals electric trailer brakes and an.
This 6 way round trailer wiring socket is equipped with a locking tab on the inside of the dust cover that secures the plug in place when inserted. The basic purpose remains the same whether your truck and trailer is using a 4 way 5 way 6 way or 7 way connector. 6 way plug wiring diagr am standard wiring post purpose wire color tm park lights brown gd ground black or white s trailer brakes blue lt left turnbrake light yellow rt right turnbrake light green a accessory red the most common variances on this diagram will be the bluebrake redacc wires will be inverted. 7 way connectors allow for all functions provided by 6 way connectors three basic lighting functions electric brakes and additional power supply with the seventh wire for backup lights. 6 way systems round plug round 1 14 diameter metal connector allows 1 or 2 additional wiring and lighting functions such as back up lights auxiliary 12v power or electric brakes. Right turn left turn ground tailmarker brake battery.
You will have the following functions. Trailer electrical connectors come in a variety of shapes and sizes.