Junction Box to Clean Up Wiring on Old Trailer

Updated 02/24/2026 | Published 02/20/2026

Products Featured in This Question

TowSmart 7-Blade Trailer Connector w/ Jacketed Cable - Trailer End - 72" Long

(8)

$37.15

etrailer Trailer Wiring Junction Box - 7 Terminal

(131)

$17.49

Question:

HI guys, I have a new 7 blade trailer end replacement cable plug. Its about six long. What is best way to cut off the last 4 ft or so of the old trailer cable end and replace it with the new one. In other words I need to splice the new cable on the ends of the old trailer cable. Is there a junction box, like in house wiring to make the connection? Thanks, Craig

asked by: Craig K

Expert Reply:

That’s a great question, and you’re definitely on the right track wanting to do this cleanly instead of just taping a bunch of butt connectors together. The easiest and most professional way to splice your new 7-blade cable into the existing trailer wiring is by using a junction box. I’d recommend the etrailer Trailer Wiring Junction Box Part # e99009. It’s basically a small, weather-resistant box that mounts to your trailer frame near the tongue and gives you clearly labeled terminals for each circuit, ground, brakes, 12V power, left turn, right turn, etc.

You would cut the old cable back to clean wire, run those wires into one side of the box, then run your new 7-way cable into the other side. Inside the box, you simply attach each wire to the correct terminal post and tighten everything down. It keeps all your connections protected from moisture and corrosion, makes troubleshooting much easier down the road, and looks a whole lot cleaner than open splices. It’s definitely the best long-term solution for this type of repair.

expert reply by: Heather A