curious , so I had a look at that $100 harness system of parts and I am not impressed. 100 greenbacks is about 130 canucks, and for that I can buy ALL the wiring,lights and mounting hardware to wire up a trailer.
One problem with that 'modular' wiring system is the number of exposed 'plug and pray 'connections. Up here we get a LOT of salt dumped onto the roads in winter, eats steel and copper...
Another problem with that harness is that it doesn't allow for backup lights even though it is at the 7way RV plug. A 'pet peeve' of mine is that no mfr actually includes backup wiring ,let alone lights in their $$ trailers. If you think they're not needed, please come here and backup my 6by10 dumper 250' into the woods at night. BTW thoseedge of the roadway dropoffs are 4-5' deep !
Total wiring of a new trailer should take less than 2 hours and that includes couple coffee breaks. I've got a 22 years old trailer here still running the same wiring though it has a couple 'replaced' rear lights....oopsy.
That's your opinion, but after I used their harnesses on my drop deck and flatbed trailers, I never had to touch that part of the wiring for the following two years I had them, and my buddy that used the linked harness on his trailer loved it and hasn't had one problem with it and said it was worth every penny.
As far as exposed connections, the only connections other than the plugs that plug into the lights, is the main harness connections. IF you put them together properly, with the recommended silicone grease, and it is aligned properly, it isn't going to get moisture ir salt into it. I even added a sleeve of adhesive lined shrink tube over the connectors for extra protection. After over 40 years of maintaining over the road tractors and trailers, I learned that lesson.
Also, if you fabricate the harness from scratch, depending on the type of lights you use you'll have a whole lot of connections where the harness wires connect to the pigtails that plug into the lights, and three way connectors or connections where drops have to come off for markers, turn lights or stop lights. In the harness, those are all contained in the injection molded junctions. I have never had one of those fail.
Maybe you could wire a trailer in two hours, but it has taken me most of a day using single or flat multi-conductor wires by the time I ran all the wires, made all the connections and sealed or shrink tubed them, then secured everything so it's not going to catch on anything and be supported and protected so it's not going to chafe. Been there, done that. But then I'm pretty anal about that stuff because I hate fixing light harnesses.
