Modern in bumper trailer plug harness

[wearsabrowncoat]

It was time to update the trailer wiring on my rig. I never liked the loose flat 4 pigtail from the factory and once the Slee rear was added it required the swing out to be open to plug the trailer wiring in. Because I have dragged the rear bumper on many departures I couldn’t utilize one of those flimsy metal trailer brackets that hangs below the bumper nor do I like the look. I had been eyeing the clean look of the 7/4 outlets on newer Toyota trucks with the factory tow option so that was what I was going for.

Although this was installed on a first gen Slee rear bumper the info should be useful for other after market bumpers as well as the factory bumper.

 

[wearsabrowncoat]

This Hopkins part (#41144) was ordered from Amazon. It is labeled for Chevys but it looks exactly like all the newer Tacoma and Tundra factory harnesses I have seen. Regardless of whether there is an actual Toyota parts kit out there you will still have to cut and splice since the factory wiring (flat 4) will not plug and play into this newer dual style connector so I settled on this part once I found it.

 

[wearsabrowncoat]

Out of package

 

[wearsabrowncoat]

Hole saw needed

 

[wearsabrowncoat]

I drilled from inside the frame with a right angle drill and various socket extensions.

 

[wearsabrowncoat]

That was to avoid the factory angled support bracket

 

[wearsabrowncoat]

And provide access for the rear plug in connector via the factory hole in the angled support bracket

 

[wearsabrowncoat]

If you don’t have a right angle drill you can drill from the outside by making the center of the circular hole approximately 13” from the center of youtr receiver hitch

 

[wearsabrowncoat]

There is no template with the kit since it is designed to fit in an existing factory hole so you need to make your own. The more time you spend perfecting the template the easier your cutting and fitting will go. I used some clear plastic from some bubble wrap type packaging. It was firm enough to get an accurate fit and also easy to see where there was interference. This photo is after the cutting and grinding thus the deformed melted look.

 

[wearsabrowncoat]

I cut the rectangular portion of the hole using a combination of tools including a sawzall, angle grinder, and dremel with cutoff wheel. The most effective was the saw all with a stubby blade. I made this blade from a previously mangled blade and don’t think they sell them anywhere this short. It provided enough room so the blade wouldn’t bang against the rear angled support bracket as it reciprocated back and forth.

 

[wearsabrowncoat]

The harness had some metal locking tabs that I removed and bent much wider to account for the extra thickness of an after market bumper. These things were designed for a much thinner plastic or sheet metal material. The picture below is after bending and is for reference only. Do not reinstall the metal tabs until later.

 

[wearsabrowncoat]

Paint to prevent rust

 

[wearsabrowncoat]

This black semi gloss is a decent match for most of the powder coat on my armor. If you are careful the color really doesn’t matter as the housing covers the hole but I am notorious for poor tape, running, and overspray

 

[wearsabrowncoat]

The metal tabs don’t have enough room to squeeze in and pop out as designed so attach them from inside once the connector housing is installed in the bumper. I have meat fist sized hands and the top tab cannot be seen but I had enough room to work by feel.

 

[wearsabrowncoat]

I do not have a brake controller at this time so I only connected the wires for basic trailer lights. If anyone has a recommendation for a good brake controller please chime in.

 

[wearsabrowncoat]

The cutout in the slee bumper is probably only meant to provide access for the spare tire mechanism but I used it from day 1 to tuck the flat 4 pigtail up and out of harms way. It worked ok but the bumper had to be opened to access and there wasn’t a lot of room to grab it when connecting the trailer plug. I often found myself man handling the wire to get it to connect.

 

[wearsabrowncoat]

This broken ground explains why my trailer lights were struggling. Too much wear and tear from that tight space and always pulling on it to have a little more room to plug in the trailer connector.

 

[wearsabrowncoat]

The new harness and the factory harness colors do correspond.

White: ground
Brown: taillights
Yellow: left turn/stop
Green: right turn/stop

The other wires will remain unused pending brake controller install.

 

[wearsabrowncoat]

Final picture shows after cutting the factory harness, splicing into the new harness, wrapping all splices and wire loom/wire bundle in tape, securing with zip ties, and plugging into the connector on the back of the bumper outlet.

 

[fj4068]

I do not have a brake controller so I will only be connecting the wires for basic lights at this time. If anyone has a recommendation for a good brake controller please chime in.

Thanks for documenting your install. The 7/4 outlet and the wiring for electric brakes, charge & reverse lamps is on my to-do list.

I like the RedArc Tow Pro in the LX570 because it works great and the remotely mounted control knob can be mounted in a ergonomic location. Will probably put a RedArc in the 80 when I get around to installing the 7/4 pin trailer plug outlet.