Sprinter umbilical

[BauerAP]

Wondering if anyone knows how to access the trailer side of the 7-way. I can trace it past the junction box on the king pin but don’t know where it goes from there. Looks like under the wardrobe in the master. I really don’t want to remove the entire front fiberglass piece to access it. I can pull maybe 4-6” but don’t hear where is it moving to give me a good indication.

We have a trip coming up that we will be arriving at night and would like to add a 8” led bar to the rear. I did this previously but could trace the wire into the front compartment on the last 5er. The functionality of throwing the truck in reverse and the light coming on is worth a little extra work but I don’t want to tear into anything too much.

Or any ideas on how to pull a wire from the junction box to the front compartment to run it down the frame.

2019 sprinter 32fwbh

[JRTJH]

Our 7 pin cable is routed to the inside of the pinbox and terminates there. We have a 4x4 steel "electrical utility box" mounted inside the pinbox and the trailer wiring is connected to the umbilical wiring inside that utility box. It's silver color, difficult to miss..... If your trailer has the plastic faring over the pinbox, you may have to remove that faring to access the pinbox.

When I routed the cables for our rear camera, I used a steel electrical "fish wire" and drilled a hole in the wooden cover over the front access door, fished the wire through to the pinbox, pulled a nylon rope through to the trailer, then pulled the camera cable to the pinbox with the rope. There was no way to push the fish wire through from the pinbox because of the way it is mounted. So, I had to "work backwards" to get to the front....

[BauerAP]

That’s exactly what I’m thinking. I need to connect to the yellow/center wire in the junction box.

I guess I’ll see if I can shove a fish tape through the hole where it goes towards the rear of the trailer wiring in hopes it will come out in the front compartment.

[JRTJH]

The way my pinbox is constructed, I couldn't get a "straight shot" to push the fish wire through from the front. It kept angling toward the upper deck floor and ripping through the insulation. I had to go into the front compartment and "push the fish wire through a small hole (about 2") that I drilled in the wood cover above the front access door. That way I could keep the fish wire below the fiberglass insulation. Once I had the cable in place, I just cut a 4x4 inch cover with a 3/8 inch hole in the center and a slit from the edge to the hole. Slipped that over the 2" hole and used 4 screws to hold it in place. Then a little sealant to complete the job by sealing the slit and the rest of the hole. It's not like anyone is going to crawl into the front compartment, turn around and look up anyway LOL