On our Compact, as delivered with the original plug I faced some "challenges" with the wiring. What I ended up doing was to remove the original plug and about 2 feet of the original wire harness, add a waterproof junction box to the frame rail under the nose box and trace each trailer circuit with a probe tester and label it as I wired it into the box.
Our trailer had just brake/tail on the brake/tail, with the turns on a separate circuit to the smaller amber lights. This was giving me a headache with wiring the flat 7-way connector properly so I combined the brake/turn signals to conform to USA wiring standards and rewired the smaller lights as backup lights using the correct circuit on the 7-way and a couple of clear LED lights.
Once I got the basics sorted out, I added the charge and brake circuits and ran wired up a "pigtail" with the trailer connector on it from the junction box to the front of the trailer.
Overall, it wasn't particularly difficult but I did need to go slow and think about what I was doing to make sense of the original wiring.
Our trailer had just brake/tail on the brake/tail, with the turns on a separate circuit to the smaller amber lights. This was giving me a headache with wiring the flat 7-way connector properly so I combined the brake/turn signals to conform to USA wiring standards and rewired the smaller lights as backup lights using the correct circuit on the 7-way and a couple of clear LED lights.
Once I got the basics sorted out, I added the charge and brake circuits and ran wired up a "pigtail" with the trailer connector on it from the junction box to the front of the trailer.
Overall, it wasn't particularly difficult but I did need to go slow and think about what I was doing to make sense of the original wiring.