Trailers with brakes typically connect to tow vehicles with a 7-conductor cable. The cable connects to a socket on the tow vehicle with pins. On a recent trip, the cable got into the space in front of the trailer ball and got pinched.
I ordered a replacement from Amazon.
The first step was to grok the current setup. I cleared out the front closet and folded the slant board down to get the wiring. The 7-pin cable and a wire loom exit the front of the Casita. Removing the stress relief and opening up the loom showed the two wires that go to the emergency break-away switch for the brakes. Looking at the inside, most thing made sense, except for two:
- There was a blue wire connecting to a black wire? (I added blue 3M painting tape to those two for reference after I cut the wires).
- In addition to the 7-pin, there were four, not two wires entering the wall.
Four wires enter, two wires leave? What Mad Max Beyond Thunderdome nonsense is this?
The information sheet that came with the new cable provided the necessary clues. The “extra” wires were connected to brown, the “tail light” color — which means the running lights. I’m pretty sure the two wires that go into the wall but don’t come out are running into the shell to the front running lights. Blue is ElectricBrakes, so the black wire from the breakaway going to blue makes sense.
The next step was cutting out the old cable connections and then bench testing to see if the wire colors of the original cable matched the new one. As you can see from the sketch, they did.
Then it was just a matter of connecting the new cable to the trailer wires. (And vacuuming and putting the stuff in the closet back, but that’s boring.)
I was originally going to go marine-style and use heat-shrink butt connectors, but I remembered that the Casita doesn’t float, we’re a looong way from saltwater, and WAGO connectors are awesome. I didn’t have big enough WAGOs for the power and ground wires, so I used wire nuts. I should probably replace those someday.
Nothing works until it’s tested. We broke out the walkie-talkies and did our usual pre-trip light checks. Then turn off the converter breaker and verify we were getting tow vehicle voltage from the battery.
