Mercedes-Benz Metris Forum banner
1 - 20 of 23 Posts

·
Registered
2021 metris cargo
Joined
·
6 Posts
Discussion Starter · #1 ·
i read a lot of discussion about the existence or not of a harness included with the factory trailer hitch for connecting an electric brake controller. several folks expressed locations that others could not verify.

today, we found the actual trailer brake controller harness and wire connector that was installed by the factory in my 2021 Metris cargo.

after removing the glove box, we found it tucked under some harness wires against the firewall on the passenger side of course. it has four wires that will work with a standard USA trailer brake controller four wire hookup. the connector is a small green four pin connector and the tech said he has seen this same connector on other Mercedes products. i have a picture of the connector.

we installed a Curt model 51170 controller which is convenient in that it is in two parts. a controller knob/indicator for the dash mount and the actual applicator (about the size of a cigarette pack). a harness to connect the two is included with the controller. we mounted the applicator under the console cup holders. that cup holder part pops out and there is a flat plastic surface under that makes mounting simple. the knob/indicator is right below the ignition switch and i can see it through the spoke in the steering wheel.

all seven wires needed for a typical USA electric brake connector are already installed to the connector at the hitch so that part needed no work.

we used the trailer connector tester to verify all was good and everything was fine. unfortunately i did not see which of the four common wires from the applicator (white,black,red,blue) go to each of the wires from the connector. the tech cut off the factory connector and butt spliced in the four applicator wires and had that part in place while i was daydreaming i guess, sorry.

Wood Circuit component Electrical wiring Electronic component Cable
 

·
Registered
2021 metris cargo
Joined
·
6 Posts
Discussion Starter · #3 ·
the applicator has a connector on the end of the four wires. Curt offers a variety of adapter cables that connect to this connector and have the correct connector on the other end to fit to the existing trailer brake wiring installed by a factory. although there are a lot of adapter cables available, truthfully, most of them are for pickup trucks and some of the full size SUV's commonly used for trailer towing in the USA. i have not researched recently but i do recall that there were not many available for autos or foreign cars in general.

i was able to purchase a direct cable adapter for a GMC pickup i did my own install on a few years ago. it certainly makes life easy. basically mount the controller and plug in the cable.

in any case, the tech did not have an adapter cable even if Curt offered one. i got the impression that although he said Mercedes had used this same connector and wiring setup for years, he gave no indication that an adapter cable was available.

so, he just cut off the wires near the connector, stripped them and then butt splice connected them to the corresponding stripped wires from the factory adapter connector.
 

·
Super Moderator
2019 Passenger
Joined
·
2,120 Posts
Makes sense. I see the connector for Tekonsha, but a Curt version seems harder to locate.

What sort of trailer do you intend to tow?
 

·
Registered
2021 metris cargo
Joined
·
6 Posts
Discussion Starter · #5 ·
i have a general purpose twenty foot, flat bed trailer. it has two axles, a wood floor and home made metal side rails. i have added lots of tie down hooks in various places. it has a small winch on the front of the bed. it is about twenty five years old.
i have pulled it with my Ram pickup, my Jeep Cherokee, but i most often pulled it with my Chevy Astro van. i bought the Metris because i felt it was the closest match to my old Astro, a vehicle i loved and drove until it finally became un trust worthy for distance travel.
i use it for hauling some of my modest classic car collection vehicles that vary from a Chevy Malibu to an original Mini Cooper with a couple others in between those sizes. i use it for landscape materials, helping friends and family move furniture and even a motorcycle once in a while. we weighed it once years ago and recall it was around 1500 pounds empty. it has electric brakes on one axle.
when its empty, i try to set the brakes so they just barely drag. in the past getting this right was a bit fussy. will have to see how this new digital controller operates. definitely need the electric brakes when i have a car on the trailer.
i also plan to try hauling a small travel trailer. i have researched trailers and i have found several single axle trailers that are well within the 5K limit for the Metris i think i will try to rent one or two different ones to see how it goes before i buy something. the ones i have looked at are very nice, around twenty foot and are big enough for just two people.
 

·
Super Moderator
Metris Cargo 135 2020
Joined
·
1,002 Posts
Cool stuff.

Could we see the face of the plug?

Looks like some kind of a square with an orientation peg on it.

Would it mate to this ...

Product Cable Electronic device Electrical wiring Wire


( Tecumseh 3063-P for Sprinters )
 

·
Registered
2021 metris cargo
Joined
·
6 Posts
Discussion Starter · #8 ·
wow, that makes sense, Mercedes would use the same connector on a sprinter and on any vehicle with a trailer hitch. manufacturers try to keep things as simple as possible. bingo, connecting a trailer brake controller to a sprinter or a Metris is a piece of cake once you dig around under the glove box and find the connector. i would say this looks like an exact mating match to me. see photo for yourself.
Circuit component Electronic component Electronic engineering Gadget Technology
 

·
Super Moderator
Metris Cargo 135 2020
Joined
·
1,002 Posts
Yes :)

And, now I'm happy that should I go down this road with either of my vehicles, once I have a trailer with brakes, that I can go the plug and play route. Yippie!
 

·
Registered
Joined
·
1,289 Posts
And none of this applies to my '18, right? -- it wasn't until '20 or '21 that they redid the hitch wiring?
 

·
Super Moderator
Metris Cargo 135 2020
Joined
·
1,002 Posts
I vaguely recall something about a change for maybe? MY'20, that finally all 7 pins were on in the back ... 🤔
Might take some digging to find that tidbit.
 

·
Registered
Joined
·
19 Posts
Not sure if cutting into the wiring harness will void the factory warranty besides the missing brake pin (7) wire is there even a way to drag a trailer of weight with the 2" receiver 5-3/4" off the road safely? Anyone installed the crazy steel block fix, aftermarket lift kit so to install a tire with some tread? Why no factory airbags? Just about everything on my 20' is "half baked"
Can anyone in the car industry explain the purpose of $178.00 triangle windows infront of the door mirrors??? (Dash trash level view port)?
 

·
Registered
Joined
·
1 Posts
Boy I wish you had included a photo of the exact location. I also have a 2021 cargo, and I've spent hours looking behind the glove box to find nothing. Can you tell us any more about where to look?
 

·
Registered
Joined
·
19 Posts
I believe an integrated trailer brake controller that can be adjusted through the infotainment screen and ties directly into the van's ECU will soon be standard on tow packages. This will be more precise, convenient and cleaner than aftermarket accelerometer based systems
 

·
Super Moderator
2019 Passenger
Joined
·
2,120 Posts
that can be adjusted through the infotainment screen
I hope not. I want a stupid head unit so when I remove it I lose nothing. That said if MB gives us a V Class dash and 15" screen I might be ok with it... but only if wireless AAuto works 100%. So, really, please keep the head unit basic.
 

·
Registered
Joined
·
19 Posts
My Ford Maverick with 4K tow package a has this. I asked specifically when ordering the Metris and was told if I was rolled into a 2023 I could likely get it with the tow
 

·
Super Moderator
2019 Passenger
Joined
·
2,120 Posts
My Ford Maverick with 4K tow package a has this. I asked specifically when ordering the Metris and was told if I was rolled into a 2023 I could likely get it with the tow
I understand. I just hope they do not add features like this to the head unit because the net result is that you end up with less options and less enjoyable entertainment system.
 

·
Super Moderator
2019 Passenger
Joined
·
2,120 Posts
It’s very convenient. Easy to fine tune. And more accurate than accelerometer based systems. Win win win imo.
Well, on your Ford I think people are not seeing that as a win win. There is a recall. Trailer Brake controller NFG


Proportional brake controllers are the safest on the road. They use accelerometers. Most of the modern controllers use 3 axis accelerometers so the mounting orientation is not an impact like some older models. Similar products as the Curt above are available from 3 different companies with fine tuning using remote controls or mobile applications using bluetooth etc.

Since you do no own a van yet you may not have had the enjoyable experience of using the GPS, wired carplay/AAuto, bluetooth using an iPhone etc.We have an amazing after market of feature rich products to tap into to meet the various needs of the individuals. Locking features into a head unit is a massive mistake for this van. It can work for higher end vehicles that invest heavily in the creature comforts, but this van is not that. Put a Tesla screen in this van and support it with Tesla's speedy software updates then we can talk. I much prefer my Kenwood head unit over the stock offering.
 
1 - 20 of 23 Posts
Top