Can You See Me

 

Wiring up the exterior trailer lights (stop, turn, marker) and electric brakes is pretty mundane but it was going to be so much easier if I did it before installing the floor.

There are lots of different tow vehicle to trailer plug arrangements but today's standard is a 7-pin connector. My trailer really only needs five: 1) electric brakes; 2) right turn/brake; 3) left turn/brake light; 4) marker lights; 5) ground. The other 2 that I don't plan to use are: 6) backup light; and 7) 12V auxiliary power. I actually included wiring for the 12V auxiliary power but didn't hook it up since I plan to have solar charging and the batteries function better with a smart charge controller. But the wiring will be there if I change my mind later.

NOTE: the each turn/brake wiring is a single line (one for each left and right sides). The tow vehicle sorts of whether to blink or send a steady signal (indicating braking). This confused me and can influence your lighting choices. Most modern lights include multiple functions (brake, turn, running light) but old ones like the Boles didn't have turn signals so you need to sort this out. More on this in a future post.

There are a lot of different trailer harness products that include the tow vehicle to trailer connector, cable and a connection box, but from the connection box back it's all custom based on you particular layout and needs.

So I bought some 12 and 14 AWG stranded copper wire. The connection box is color coded (smart!) and it would be ideal if you could use corresponding colored wire, but it's just too cost prohibitive to have a bunch of different colored wire (copper isn't cheap). There are some cheap-ish kits available but when you read the find print they use copper-coated aluminum, not copper, wire. Buyer beware! Instead I bought a set of colored electrical tape from Home Depot to mark the wires.

NOTE: the home depot tape kit did not include brown so instead I used yellow to marker wires on the trailer. This could be confusing because yellow is the off-the-self connector color for reverse lights. But I'm not using reverse so it was not confusing to me.

Stringing the wire was pretty straight forward. The most complicated run was the marker lights. The Boles has the four typical side markers, plus there's the two rear running light. Three when you count the 1948 stop light that was center mounted (they didn't have turn signals on trailers in 1948).

NOTE: my trailer lights are self-grounded so there is no return run required. They ground themselves through the light fixture housing to trailer connection (i.e. the screws holding the light fixture to the trailer). This is fine for 12V DC but you wouldn't want to run a 120V AC circuit like that.

Part Way through stringing the wires

I used some cool "butt connectors" to make wire splices. They are the heat shrink variety but in the center they have a bit of solder so that when they get heated so shrink and seal the connection the solder melts creating a very solid electrical and mechanical connection that is waterproof.

After running all the wires I wrapped the parallel runs with harness tape. And anywhere a run went through a narrow hole I reinforced with harness tape in order to slow down any wear. When I'd removed the original wires I notice at least one location where the wire jacket had worn through, surely creating an intermittent short. Not a danger but the blinking light would be annoying and nearly impossible to troubleshoot.

Wire wrapped harness (with ungrounded white ground wire)

I secured all the other runs and made sure they were marker wire appropriately colored electrical tape. And then connected the main harness to the interface box I'd purchased.

Marker light wiring at front of trailer

Electric brake line running from main harness to passenger side wheel well

Interface box

Marker lights, left & right turn/brake lights at rear

I'll probably need to circle back and shorten the tow vehicle to trailer cable. It's eight feet long and I'll probably only need about four feet. But it'll work as it is now, and that'll be easy to remedy so it can wait for later. Also, I bought a "plug guard" which is essentially someplace to protect the connecter end from the elements when it's not in use. I still need to drill a couple holes and mount it.

I'll write a future post on the trailer lights themselves as they are a story in themselves.