Removing & (Eventually) Relocating the 7-Pin Trailer Wire Connector

[AndrewFromIdaho]

If you have the factory hitch and trailer wiring, you may have noticed that the location of the 7-pin connector makes it somewhere between impossible and an incredible PITA to use a locking hitch pin. There just simply isn't much space.

I don't haul a trailer with my 2022 VS30 4x4 much, but I do attach a bike rack quite frequently. And I do worry that some day, someone will see my unsecured bike rack on the back of my van, and decide to walk away with it.

After dealing with it for 3-years, I finally decided to remove and (eventually) relocate the 7-pin connector.



I found a good overview from Owl Vans here. They remove the 7-pin connector, and attach it to the bottom of their step. I have a factory step, but at least the removal process is quite similar.

I figured I'd document mine here.

Step 1 is to remove the 7-pin connector from its bracket. This is a 2-step process. First, remove the 4 torx-bolts that attach the connector to the bracket, then remove the connector from the wiring harness so that you can fully remove it from the bracket and not risk damaging it while you grind off the bracket.

Astute readers will notice that my 7-pin connector is chipped. No idea how that happened, but it was sometime beofore I started this project.






To remove the 7-pin connector from the harness, you need to pull out the little red tab, and pull up a catch inside this plug. Then curse and wiggle them apart.



Continued in the next post becuase I ran out of photos.

 

[AndrewFromIdaho]

Once you've done that, you can wriggle the wiring harness fully out of the bracket. Though, it takes a bit of wriggling.



The harness is attached to the tow hitch with an Official™ Mercedes Benz Zip Tie. Probably $60 from your local dealer.



Your next step is going to be using a cutoff wheel/disc to cut off the bracket from the trailer hitch. You're probably better at this, and more careful than me. But I wanted to minimize my chances of accidentally cutting off anything that didn't need cutting, like my bumper. So I used a combination of masking tape and cardboard to make it clear where I wanted to make my cuts, and what needed to be protected from a little slip of the cutting wheel.





Now, get cutting. BUT NOT BEFORE YOU PUT ON EYE PROTECTION. And gloves. And long sleeves. But ESPECIALLY EYE protection. You're gonna be flinging molten bits of sharp metal everywhere. If one gets in your eye, you're gonna have a bad time.

 

[AndrewFromIdaho]

When you're done, you should end up with something like this. But probably tidier because you're more skilled with a cutoff disc than me.





Obviously if you just leave things like that it'll look pretty rough, and rust. (Though, my hitch had already started that process to an extent).

The helpful paint guy at my local hardware store recomended the "Stops Rust" line of Rust-Oleum spray paint ($7.99) - and I guessed that flat protective enamel was pretty close to what Mercedes puts on in the factory. Turned out good enough that I touched up some of the worn and rusting bits of the rest of the hitch.



Oh - forgot until I saw it in this photo, but a creeper is really nice to have in the cutting process.

For now I've relocated my 7-pin connector back behind my hitch with a (non-OEM-approved) zip-tie. I haven't fully decided where I'll mount it permanently, but I saved the enclosure, and it should be pretty easy to screw back onto the hitch with a couple tap screws when I'm ready.

At the moment, I'm enjoying being able to attach my bike rack swingarm to my van without the 7-pin connector housing getting in the way.





Also, for anyone wondering, the clearances with the 1Up RackAttack XL and the Recon Rack 6-bike work really well with the sprinter's rear doors. I added these ratchet straps and mounted them on the ends of the Recon Racks for extra stability. Our first road trip with this setup is this weekend, I'll come back and update if we have any issues.

 

[Gripster]

Thanks for the post

 

[mrfish27]

If you're buying zip ties from the dealer ... yeah, there's no hope for you.

Paint looks great.

 

[Maslin]

Those big zip ties are only $5.34 a piece

Some of the smaller ones are like $18.

 

[Dax Travels]

Angle grinder with a flap wheel makes one "more skilled with a cutoff disc", FWIW. Just a cosmetic note, it won't make your van faster or get better MPG.

 

[mrfish27]

Here's another way to do it:

 

[gltrimble]

I just flipped my 7 pin receptacle upside down to provide room for my locking hitch pin.

 

[Road Ranger]

Here's another way to do it:

I think the issue is that the 1UP Bike Rack has a threaded hitch pin designed to stabilize the rack and reduce wobble which is not amenable to the low profile lock in your photo.

I’ve tried to find an aftermarket locking pin similar to your photo but also incorporating the threaded feature that 1UP uses to stiffen up their rack and had no luck finding anything.

My solution so far has been to unscrew the 7-pin connector but leave it in place which allows it to move just enough to engage the 1UP threaded hitch pin.

A relocation of the 7-pin altogether seems the more elegant solution.

 

[The_D]

I think the issue is that the 1UP Bike Rack has a threaded hitch pin designed to stabilize the rack and reduce wobble which is not amenable to the low profile lock in your photo.

I’ve tried to find an aftermarket locking pin similar to your photo but also incorporating the threaded feature that 1UP uses to stiffen up their rack and had no luck finding anything.

My solution so far has been to unscrew the 7-pin connector but leave it in place which allows it to move just enough to engage the 1UP threaded hitch pin.

A relocation of the 7-pin altogether seems the more elegant solution.

I have no problem using bike rack and the following type pin https://www.etrailer.com/Trailer-Hi...Stlqp73u61QMIMU36slYPXA6W_w99s9hoCL5IQAvD_BwE

It works with one-up /velocirax/ Thule and any other bike rack I have with threaded expansion pin or without
Key part goes on the left.