How-To: Cleanly install a Non-Factory CX-5 Trailer Harness

howlin4you

Member
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2014 Mazda CX-5 Touring AWD
Another member asked me how I installed my trailer light plug and after typing it up and sending him a PM it was suggested that I post this in the how-to section. Hopefully this can help someone out.

First, I installed one of these and ran it through a pre-existing hole in the body under the spare tire:

https://www.amazon.com/dp/ (commissions earned)

Then at the end of that I attached one of these:

https://www.amazon.com/dp/ (commissions earned)

I mounted it to the car with this (there are two metal brackets on the forward side of the rear bumper that provide support, they are attached to the bumper with those black plastic rivet things. I removed one rivet thing and ran a bolt through the Hopkins mounting bracket, the bumper, and the metal support bracket. For the second hole in the mounting bracket I drilled a hole in the bumper and ran a bolt through with a large washer and a nut):

https://www.amazon.com/dp/ (commissions earned)

The reason for the 12" extension was that the end of the Curt vehicle adapter did not sit nicely in the Hopkins mounting bracket. To solve that I added in the extension so the Hopkins plug was in the Hopkins bracket (it fits nice and snug since they were obviously designed for each other).

I wanted a dust cover for it too and there is provisions in the Hopkins mounting bracket for a simple one but I wanted something a little different, so I bought a Hopkins version of one of these (I bought it local and couldn't find the exact thing on Amazon but it's basically this):

https://www.amazon.com/dp/ (commissions earned)

The tester I have has a lanyard on it (just like the one pictured on Amazon) that works perfectly with the Hopkins plug and Hopkins mounting bracket. Basically I plug it in as a dust plug and when not in use it just dangles out of the way.

Here are some pictures (it's winter in Wisconsin, the car is a little dirty) -

This is the hardware holding the mounting bracket on. When it is run through the existing bumper support bracket it is very solid and secure.

BracketMounting.jpg


This is the pre-existing hole and grommet under the spare tire. Just remove the grommet, slit it halfway with a razor blade, run the wire through, and re-install.

UnderSpareTire.jpg


This picture shows the Hopkins extension connected and tie wrapped to the hitch.

FromBelow.jpg


The light tester/dust cover installed from below/behind.

DustCover.jpg


Overview.

FromFurtherAway.jpg


Up closer.

UpClose.jpg


I hope I explained it well enough for anyone that needs it. Feel free to ask me any questions you may have.
-Ryan
 
CX5 hitch and wiring

Ryan,

I read your writeup, but it didn't cover the installation of the hitch itself (or maybe I missed it).

Did you install the hitch yourself? Is it a bolt on unit, and what is the rated capacity of the one you got.
Can you tell me the total cost not including your labor to buy the hitch and associated wiring?

thanks in advance for your time.

Mike Steinzig
 
There are plenty of threads dedicated to installing the hitch itself. I didn't feel I had anything to add.

It is the Curt model, I don't recall the rated capacity.

Total cost was something around $220 with almost everything bought from amazon.com
 
Thanks I used this to do mine a few weeks ago and it's a good write up. I don't have wires and s*** hanging ghetto looking so many aftermarket harness installs I see.
 
What is the reason for the converter box, as opposed to splicing directly into the wires going to the tail light bulbs and simply using a 4 wire system? Will it mess with the ABS?
 
Trailers in the US use one filament for brake light and turn signal. Mazda like most cars has two separate bulbs. The converter box combines them. A powered converter has the extra advantage that the trailer lights are on a different fuse so if something goes wrong with the trailer lights the car is still OK
 
Trailers in the US use one filament for brake light and turn signal. Mazda like most cars has two separate bulbs. The converter box combines them. A powered converter has the extra advantage that the trailer lights are on a different fuse so if something goes wrong with the trailer lights the car is still OK

Well that makes perfect sense, thank you!
Curt hitch installed per etrailers video with a friends help in 20 min. Now to order a converter.
 
Anyone put some silicon or sealant on the sliced grommet under tire?

Do you mean for extra sealing? I did not, as the rubber grommet provides a good enough seal as it's squeezed into the hole, and assuming you don't make too big a hole for the wires. But, I can't see how any extra sealing can hurt. Maybe just a little messier ;)
 
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Do you mean for extra sealing? I did not, as the rubber grommet provides a good enough seal as it's squeezed into the hole, and assuming you don't make too big a hole for the wires. But, I can't see how any extra sealing can hurt. Maybe just a little messier ;)

Thanks!! Probably gonna do that project next week. I'll see how it looks before I worry about it. I imagine water intrusion from that area is highly likely unless one was fording streams. :)
 
Sure no prob, if you get stuck on a section, gimme a shout! Like mentioned above, there is a heat shield right below the grommetted hole. Good luck (thumb)
 
I picked up a bunch of wire loom at HF for the project. It's dirt cheap there for that stuff.

I'm always paranoid of shorts due to wire abrasion.

1830_primary.jpg
 
Take some pics if you get the chance. I'm a big believer of over engineering vs. under engineering and being a little more conservative than aggressive. At least when it comes down to automotive/mechanical/ safety mods (drinks)
 
I will take some pics!! Not concerned about the wiring part but worried I might mess up the trim plastics so gonna be extra careful when I pull things out.

After I get the harness installed I was going to put these scuff plates on. I figured I would wait to install since I have to take these trim pieces off for harness.

$_12.JPG

$_12.JPG
 
Those are pretty interesting! As far as the plastics, while it takes a little experience to pull only with a certain amount of force, just remember it can be replaced. Sometimes you have to make mistakes to learn. That being said, the rear plates, to me, came off fairly easy, with less force needed that the door side plastic plates.
 
I am still waiting for the remaining pieces of howlin4you's clean connector mount to arrive. This might a post Labor Day weekend project.
 
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