Wiring 4 Wires on Trailer to 7-Way Connector

Updated 07/17/2018 | Published 07/15/2018

Question:

My trailer has 4 wires going to a 7 blade connector that has red,blue,black,green,brown and white .only four color wire white ,brown ,green and yellow what goes where?

asked by: Anthony

Expert Reply:

Most likely on your trailer the brown wire is for running lights, the green wire is for right turn/brake light, the yellow is for left turn/brake, and the white wire is for ground. Because previous owners or trailer manufacturers may have installed different color wiring than what is standard, it is always a good idea to test the wires for function to be sure. You can apply 12V power to the trailer wires to see what function each of them activates.

If you are wiring these to a 7-Way connector on your trailer, the running lights wire will go to the 11 o'clock position at the back of the connector. The right turn/brake wire will go to the 3 o'clock position and the left turn/brake wire will go to the 9 o'clock position. The ground wire will be secured at the 7 o'clock position.

I have attached an image of a standard trailer side 7-Way connector to clarify these connections.

If you aren't looking to connect the wires on your trailer to a trailer-side 7-Way, but are instead needing to connect a 7-Way that is on the tow vehicle to the trailer's 4-Way, a better option is with an adapter like the Pollak # PK12716. This will plug right into the vehicle's 7-Way and provide a 4-Way at the other end to connect to the trailer.

expert reply by: Chris R