Looking For Trailer Side 7-Way Wiring Harness For Car hauler Trailer

Updated 05/18/2026 | Published 05/11/2026

Products Featured in This Question

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

(435)

$62.99

12 Gauge 7 Conductor Jacketed Wire - Per Foot

(522)

$10.36

Steel Tubing Clamp - 1/2" Diameter - Qty 1

(10)

$1.40

TowSmart Wire Loom, 1/2" Diameter, 10' Long

(2)

$6.54

Question:

I have a wide car hauler trailer with electric brakes and am trying to find a 7-way replacement wiring kit for the entire trailer. Your website search filter is terrible gives me 2500 results and should get about a dozen.

asked by: Bradley P

Expert Reply:

Hey Bradley, thanks for reaching out. We do have the stuff you need to replace the 7-way harness on your car hauler. The best way to do that is to run all your connections thru a junction box then use jacketed 7-wire to connect all your lights and brakes. Here is what I recommend:

- etrailer Trailer Wiring 7-Way Upgrade Kit w/ Junction Box and RV Style Connector # e99011

- 12 Gauge 7 Conductor Jacketed Wire - Per Foot # DW04914-1

The 7-wire is sold by the foot so I'd measure the distance from the junction box mount location to the lights and order a few more feet than you think you need just to be safe. For a nice, clean install I'd recommend grabbing some wire loom # TS69QR and loom clamps # SWC9022-1 for securing everything.

Also, yes, I know what you mean about our search sometimes it doesn't like to cooperate for stuff like this. It's something we are constantly working on and trying to improve. Sorry for any headache it caused.

Let me know if you have any other questions.

expert reply by: Jesse M

etrailer Trailer Wiring 7-Way Upgrade Kit w/ Junction Box and RV Style Connector
(click to enlarge)

Christos

5/13/2026

I bought this etrailer Trailer Wiring 7-Way Upgrade Kit w/ Junction Box and RV Style Connector Part Number: e99011 and it was a breeze to install. I have little to no experience doing any kind of trailer wiring before hand. I was replacing a junction box that was a mess inside, just a bunch of jumbled wires. This new part was very nicely color coded making it so much easier to help identify any future issues that may come up. I would. Highly recommend this product, the customer service at etrailer is also second to none.

Jesse M.

5/18/2026

@Christos Nice! Glad to hear the junction box worked out for you and that you were able to get it done so easily. Also, thanks for your kind words. I appreciate that. Don't hesitate to reach out if you ever need anything!

Derek B.

5/13/2026

The 7 way junction box is the way to go. Color coded and easy to connect your new wiring. Get some good wire strippers, heat shrink terminal ends and crimpers.