How-To install trailer lights for your Tiny House

Part of successfully building a tiny house trailer is making sure that the actual trailer is street legal including weight limits, width, height, and length allowances, proper lighting, and safe wheels and tires. While we have already sandblasted our trailer, primed and painted it, replaced an old tire (which we have now decided to replace them all), and added new leaf springs and hardware, it was time this past Saturday to add the proper lights for breaking, turning, and otherwise signaling.

A week ago we purchased a Haul-Master Deluxe 12 Volt Trailer Light Kit from Harbor Freight for $24.99 as well as a wiring set for about $4. The extra wire was needed considering the kit was designed for a 25′ trailer and we have a 30′ trailer. The kit comes with:

  • 23 ft. split Y-style harness
  • 4 ft. color-coded trunk harness
  • Corrosion-resistant housing
  • Two built-in red marker clearance lights
  • License plate light and bracket

Our tow vehicle already has a 4-pole vehicle end for the hitch so we knew we were in business with this affordable kit. Now I would love to say that the process of installing these lights was incredibly difficult and by installing them I was showcasing my electrical prowess. Truth of the matter is it is rather easy to wire up a trailer and once you are familiar with what your hitch has, what your kit has, and what you need to be street legal, the rest is just a bit of elbow grease.

Wiring chart courtesy of Click for larger image.

In the chart above you will note that our 4-way connector involves a green wire (right turn), a yellow wire (left turn), a white wire (ground), and a brown wire (tail/marker). You can see below the run of the wires from the rear of the trailer to the tow vehicle hitch.

4-pole trailer end -and- 4-pole vehicle end


So how do you run the wires?

  1. If no wiring holes are present on your trailer first drill holes suitable for the screws included in kit.
  2. Mount the Stop-Tail-Turn Light, marked “L.H.” (with the License Window), on the left rear of the trailer with its side marker to the outside of the trailer. Then, mount the License Plate Bracket with the Stop-Tail-Turn Light.
  3. Mount the Stop-Tail-Turn Light, marked “R.H.” (without the License Window), on the right rear of the trailer with its side marker to the outside of the trailer.
  4. Use the Metal Frame Clips included in the Mounting Hardware Package to mount each half of the Split Y-Style Harness down each side of the trailer. Run the YELLOW and BROWN wires down the left side and GREEN and BROWN wires down the right side of the trailer.
  5. Connect the YELLOW and BROWN wires to the left hand Stop-Tail-turn Light with the Wire Nut Connectors included in the Mounting Hardware Package.
  6. Connect the GREEN and BROWN wires to the right hand Stop-Tail-turn Light with the Wire Nut Connectors included in the Mounting Hardware Package.
  7. Attach the WHITE GROUND wire to the trailer tongue or frame.
  8. Mount the two Marker Clearance Lights in the areas shown in the illustration. Connect each wire from the Marker Clearance Lights to the BROWN wire on each half of the Split Y-Style Harness.
  9. Connect the Split Y-Style Harness Plug to the Color Coded Trunk Harness Plug.
  10. Turn on the towing vehicle’s headlights. The two Stop-Turn-Tail Lights and two Marker Clearance Lights should turn on. The brighter Stop Lights should turn on only when the vehicle’s brake pedal is depressed, or when the vehicle’s turn signal is activated (ignition key must be in its “on” position).
  11. If the Light Kit fails to illuminate, check all ground connections. If the turn signals on the Light Kit do not illuminate, check the connections between the towing vehicle’s wiring and the Color Coded Trunk Harness.

NOTE: We chose not to use the wire nuts and instead use heat shrink tubing so as to make a more solid connection that will last longer in transit and weather.

To see photos of our experience as well as a special photo of the Tiniest r(E)volution adding her experience to the mix please visit our Flickr site!


    • anotherkindofdrew says

      You are right and you can find out your answer (and more!) here:

  1. Chuck Sanders says

    A four-pin plug on a 30′ trailer?  What about your trailer brakes?  You should really be running electric brakes on something that size (at at least some sort of brake on all axles is mandatory).  That implies a standard 7-pin connector and a controller added to your tow vehicle.  Thanks for your time on the blog, and be safe!  I’d love to see your blog make the news – but not as the result of a towing accident.

    • anotherkindofdrew says

      Thank you so much for joining us at the Tiny r(E)volution Chuck. I appreciate your comments and while I don’t care for our blog to be in the news I would dislike even more us to make the news due to an accident. Our two vehicle is equipped with a proportional brake controller which will get the trailers electric brake spliced into it via the 4-pin connector. 

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