Trailer Wiring and Brake Controller

[JonathonM]

I am installing a trailer brake controller on my 2007 Hurricane Four Winds 34B as well as a 7-pin trailer electrical connection.

At the rear of the RV, near the hitch, there is a 7-pin chassis harness. This harness connects to another harness which splits into four separate harnesses:
1. LR Trail lights
2. RR Tail Lights
3. License plate lights
4. 4-pin trailer wire connection.
In addition to the 7-pin chassis harness, there is also a single blue wire that is part of the overall bundle of wires but uses a separate connection.

I intend to determine if I can repurpose the current 4-pin trailer wires/connections, if the other necessary wires for a 7-pin trailer connection are already present at the rear of the chassis.

What is the purpose/function of each of the wires in the 7-pin chassis harness? (see picture)

[Lt Dan]

Here is the standard layout for a 7pin. The blue wire may be either a dedicated 12v wire or for the brake controller. Our Workhorse chassis did not have a dedicated 12v wire so I had to run one separately.

[Parafango]

If you elect to tap into the existing wiring anywhere outside of the interior of the vehicle, and you choose to use the scotch lock suitcase connectors, consider using these that have a little di-electric goo already in them. The dielectric will help reduce oxidation at the wire penetration site.

Scotch Lock connector

[JonathonM]

Originally Posted by Lt Dan

Here is the standard layout for a 7pin. The blue wire may be either a dedicated 12v wire or for the brake controller. Our Workhorse chassis did not have a dedicated 12v wire so I had to run one separately.

Thanks Dan!
I know that I can get all signal lights from the 4-pin connections. There is also a chassis ground next to the hitch.
That leaves the brake signal (blue) and 12V Lead (black). I am just wondering if those two sources are available at the chassis harness in the picture.

[bobphoenix]

I just went through a brake controller install nightmare... (I made the mistake of thinking the cargo trailer company knew what they were doing...)

I now have a Curt "Echo" under dash controller that I finally installed myself (and abandoned mostly all of the company installed wiring...)

It is not looking likely that you have a +12V and Brake Control wires in that bundle, because those conductors are usually a minimum of 10 Ga wires where you lights are 12 - 14 Ga.

If you have the choice, (and if it were me), I would run two new conductors from firewall back... A new +12V and a new 12 Ga Blue from the controller back to a 7 pin connector. You can get a 4 - pin adapter and it will have open pins for +12V and Brakes (It will also have an center tap, usually used for back up lights.

Also, Curt may have a ready made harness for your application...