Adding Standard 7-Blade Connector To Single Axle Box Trailer With 7-Way Round Pin Connector

Updated 11/03/2025 | Published 01/01/2025

Products Featured in This Question

Pollak Black Plastic, 7-Pole, RV-Style Trailer Connector - Trailer End

(691)

$8.44

etrailer Trailer Wiring 7-Way Upgrade Kit w/ Junction Box and RV Style Connector

(361)

$56.00

Question:

Hi I have 5 wires on my single axle small box trailer my colours are Red, White, Green, Yellow and Brown, going into a 7pin female socket. Would it be easier to reconnect it or would it be easier to run a new wiring harness on the trailer to fit the 7pin plug and Socket.. Thanks.

asked by: Chris L

Box Trailer 7-Way Round Pin Connector
(click to enlarge)

Expert Reply:

Hey Chris, thanks for getting in touch. The plug in your picture is known as a 7-way round pin connector. If you are wanting to keep the wiring on the trailer as-is, and you just want to swap out the plug for a standard 7-blade, it will definitely be easier to swap out the plug only. For that, the Pollack # PK12706 you were looking at will work great. I have included a diagram showing the standard 7-way wiring/color coding.

With you having the 5 wire colors you mentioned it sounds like your trailer is only really missing the blue brake wire and black 12v wire (assuming the current connector is wired/color coated to standard). If you are wanting to add those two other wires, what I would do is add a junction box and 7-blade plug like part # e99011. This is 6' long cord with a standard 7-way. Then just run some 14 gauge wire from the junction box to the brakes.

Feel free to reach out and comment below if you need anything else or have any questions.

expert reply by: Jesse M

7-way color coding diagram
(click to enlarge)

Jesse M.

11/3/2025

Hey Chris, how did things go with swapping out the plug for the 7-blade connector on your trailer? Did the wiring diagram make it clear how to match your existing wires? Your update could make it easier for others working with a similar setup.