Electric trailer brake redux
Thread Starter
Senior Member
Joined: Feb 2012
Posts: 296
Likes: 23
From: Central coast California
2024 GLC300, 2014 BMW M235i
Electric trailer brake redux
I'm finding it totally amazing how difficult it has become to find out how to connect my electric brake controller into my vehicle. It's almost as if the manufacturer really doesn't want the vehicle owner to know. Yeah, it's there; you paid for your factory tow package, but we still don't want you to find the f**king connector.
I have my selling dealer looking and even they can't figure it out. I paid my bucks, but no joy. I was confronted with the same problem with my then new '02 Ford Exploder, equipped with factory tow package. No one seemed to know where the connector/interface was located. Finally, after months of inquires and questions, I learned that it was located in a non-intuitive location behind the glove box.
Why do the manufacturers hide this information????!!!!
3.5L (pissed)
I have my selling dealer looking and even they can't figure it out. I paid my bucks, but no joy. I was confronted with the same problem with my then new '02 Ford Exploder, equipped with factory tow package. No one seemed to know where the connector/interface was located. Finally, after months of inquires and questions, I learned that it was located in a non-intuitive location behind the glove box.
Why do the manufacturers hide this information????!!!!
3.5L (pissed)
MBWorld Fanatic!
Joined: Sep 2011
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From: East Texas
2004 Volvo XC70; 2012 GLK 350 4matic
Mercedes-Benz really does need to get a clue. Call MBUSA. Keep the line open until you have the CEO on the phone. Tell him that this is North America. Folks tow a lot of stuff with their vehicles. AND. They should deliver a fully functional towing package for the money. OR. Tell the customer they are getting half of a complete towing package. NOT. Surpise! We didn't sell you a functioning package.
Wayne
Wayne
Last edited by venchka; May 30, 2012 at 06:38 AM.
Thread Starter
Senior Member
Joined: Feb 2012
Posts: 296
Likes: 23
From: Central coast California
2024 GLC300, 2014 BMW M235i
Mercedes-Benz really does need to get a clue. Call MBUSA. Keep the line open until you have the CEO on the phone. Tell hime this is north america. Folks tow a lot of stuff with their vehicles. AND. The should deliver a fully functional towing package for the money. OR. Tell the customer they are getting half of a complete teoing package. NOT. Surpise! We didn't sell you a functioning package.
Wayne
Wayne
What a bunch of hosers.
3.5L
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Nissan GT-R BE / '12 Ducati-1199 Panigale S / '12 C300-4M Loaded/GLK350-4M Loaded
And how silly of me to think that the information would be... in the owners manual. The f**king owners manual talks about everything else, even up to some towing stuff.. but does not tell where to connect an electric brake controller. Never mind that the factory plug at the hitch has a pin labeled "electric brakes."
What a bunch of hosers.
3.5L
What a bunch of hosers.
3.5L
Newbie
Joined: May 2012
Posts: 8
Likes: 0
2012 ML350
I'm fed up with them as well. I have been trying to order the matching qwik connect plug so I can connect up my controller to my ML350. They don't seem to have one. Fortunately I have been able to find the wiring schematics on this site and will likely hard wire it myself.
Thread Starter
Senior Member
Joined: Feb 2012
Posts: 296
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From: Central coast California
2024 GLC300, 2014 BMW M235i
Suddenly, I received 2 phone calls, both this morning. The first one was from Mercedes Benz, somewhere in New Jersey (is that corporate?). The rep informed that the pin labeled electric brakes on the socket near the tow hitch is not connected to anything. He also told me that there is no connector or wiring under the dash for an electric brake controller. He said that Class II hitches rarely come wired for electric brakes so if I want them, I'll have to wire it myself.
Next, my local dealer called and said essentially the same thing.
I'm not too thrilled about pulling wire through the vehicle, so I'm considering purchasing a wireless brake controller. Still would need to supply beefy 12v to the rear socket though.
And that, folks, is the story...
3.5L
Next, my local dealer called and said essentially the same thing.
I'm not too thrilled about pulling wire through the vehicle, so I'm considering purchasing a wireless brake controller. Still would need to supply beefy 12v to the rear socket though.
And that, folks, is the story...
3.5L
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Nissan GT-R BE / '12 Ducati-1199 Panigale S / '12 C300-4M Loaded/GLK350-4M Loaded
That's completely unacceptable! What utter 
Wireless can be risky, especially with all the radio and electromagnetic interference from onboard electronics, blu-tooth and cell phones that can possibly interfere. Good luck! 
Wireless can be risky, especially with all the radio and electromagnetic interference from onboard electronics, blu-tooth and cell phones that can possibly interfere. Good luck!
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MBWorld Fanatic!
Joined: Sep 2011
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From: East Texas
2004 Volvo XC70; 2012 GLK 350 4matic
Call the Knucklehead in New Jersey. Point out to him that the Class II hitch REQUIRES brakes on the trailer to meet the 3,500 pound towing capacity of the installation. Without brakes, your towing capacity is only 1,500 pounds. You want your missing capacity.
Sign up sheets for the Trailer Hitch & Transmission Service Class Action will be handed out after class.
Wayne
Sign up sheets for the Trailer Hitch & Transmission Service Class Action will be handed out after class.
Wayne
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Thread Starter
Senior Member
Joined: Feb 2012
Posts: 296
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From: Central coast California
2024 GLC300, 2014 BMW M235i
This news certainly is disappointing, to say the least.
I just spent a few minutes disassembling the electrical connector on the hitch to confirm that there is indeed no wire going to the electric brake pin. It's true; nothing there.
This shortcoming will have to fixed, one way or another. There is no way in h*ll I'd tow my 3000 lb. tent-trailer without the electric brakes functioning. That MB delivered the vehicle in this state implies that they think it's ok to tow as much as 3500 lbs. without the trailer having brakes.
Many years ago I towed a ~2000 lb. tent-trailer with a 1991 Ford Exploder. The trailer came from the factory (Palomino) without brakes (and there was no factory option for brakes). I towed that combination for about 25k miles. There's no way I'd go beyond 2000 lbs. without trailer brakes.
3.5L
I just spent a few minutes disassembling the electrical connector on the hitch to confirm that there is indeed no wire going to the electric brake pin. It's true; nothing there.
This shortcoming will have to fixed, one way or another. There is no way in h*ll I'd tow my 3000 lb. tent-trailer without the electric brakes functioning. That MB delivered the vehicle in this state implies that they think it's ok to tow as much as 3500 lbs. without the trailer having brakes.
Many years ago I towed a ~2000 lb. tent-trailer with a 1991 Ford Exploder. The trailer came from the factory (Palomino) without brakes (and there was no factory option for brakes). I towed that combination for about 25k miles. There's no way I'd go beyond 2000 lbs. without trailer brakes.
3.5L
Thread Starter
Senior Member
Joined: Feb 2012
Posts: 296
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From: Central coast California
2024 GLC300, 2014 BMW M235i
Question: does the factory towing packing include not only the obvious tow hitch, but also additional engine and transmission cooling?
Thanks,
3.5L
Thanks,
3.5L
MBWorld Fanatic!
Joined: Sep 2011
Posts: 1,522
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From: East Texas
2004 Volvo XC70; 2012 GLK 350 4matic
I recall conflicting information. 2010 models had some kind of extra cooling. Maybe just larger fan blades. Somewhere in the 2011 or 2012 model run one of two things happened: A. All models got the extra cooling; B. No models got extra cooling.
Only a detailed parts list can solve the mystery.
Wayne
Only a detailed parts list can solve the mystery.
Wayne
Thread Starter
Senior Member
Joined: Feb 2012
Posts: 296
Likes: 23
From: Central coast California
2024 GLC300, 2014 BMW M235i
Thanks Wayne.
I have yet to tow anything with my GLK, so I'm trying to gather information that will make our first trip towing our tent-trailer stress free. I don't want to find myself worrying about our car when we find ourselves faced with pulling a long grade on a 100+ degree day.
We bought a Palomino tent-trailer new in 2000 (our second tent-trailer). We keep it stored in a hangar and haven't used it much, so it's almost like new. The data plate omitted the empty (dry) weight, only providing the GVWR number which happens to be 2890 lbs. I requested information from Palomino and the promptly responded that the empty weight is 2275 lbs. Now I have some good information to work with.
Since our GLK is rated at 3500 lbs. with the factory tow package, I feel pretty comfortable with our combination; there's a nice weight margin between what we'll be towing and the max allowable.
Now I just need to get that darned electric brake system wired up. I 100% agree that the factory should've provided it in the package, but I need to get it done myself and move on. I'm a recently retired electronics technician and I've done things like this a few times...
3.5L
I have yet to tow anything with my GLK, so I'm trying to gather information that will make our first trip towing our tent-trailer stress free. I don't want to find myself worrying about our car when we find ourselves faced with pulling a long grade on a 100+ degree day.
We bought a Palomino tent-trailer new in 2000 (our second tent-trailer). We keep it stored in a hangar and haven't used it much, so it's almost like new. The data plate omitted the empty (dry) weight, only providing the GVWR number which happens to be 2890 lbs. I requested information from Palomino and the promptly responded that the empty weight is 2275 lbs. Now I have some good information to work with.
Since our GLK is rated at 3500 lbs. with the factory tow package, I feel pretty comfortable with our combination; there's a nice weight margin between what we'll be towing and the max allowable.
Now I just need to get that darned electric brake system wired up. I 100% agree that the factory should've provided it in the package, but I need to get it done myself and move on. I'm a recently retired electronics technician and I've done things like this a few times...
3.5L
Thread Starter
Senior Member
Joined: Feb 2012
Posts: 296
Likes: 23
From: Central coast California
2024 GLC300, 2014 BMW M235i
Pin-4 in the 7-pin Bargman socket on the GLK factory towing hitch is capable of 240 watts (see page 160 in operator's manual). 240 watts @ 12vdc happens to be 20A, exactly within specifications for my electric trailer brakes and Tekonsha Prodigy RF brake controller.
From the official Tekonsha website I've learned the Prodigy RF brake controller uses pin-4 on the Bargman socket to power the brakes. It specifically mentioned that the Prodigy does not need or connect to pin-2 which is the traditional electric brake pin (and the pin not used on the GLK).
So, the Prodigy RF controller is plug-and-play - no additional wiring to the vehicle necessary.
As to the wireless security issue, you will have to satisfy your own misgivings. I have no problem with the technology. The hand unit and controller must be "paired." The controller ignores everything else. The current science of "pairing" (or "binding" as the Radio Control industry calls it) is extremely sophisticated. And, the Prodigy RF has good reviews.
Rant if you must, but please back it up with your own investigative facts.
Meanwhile, I have registered a strong complaint to MB regarding the lack of the traditional brake controller wiring in the GLK.
3.5L
From the official Tekonsha website I've learned the Prodigy RF brake controller uses pin-4 on the Bargman socket to power the brakes. It specifically mentioned that the Prodigy does not need or connect to pin-2 which is the traditional electric brake pin (and the pin not used on the GLK).
So, the Prodigy RF controller is plug-and-play - no additional wiring to the vehicle necessary.
As to the wireless security issue, you will have to satisfy your own misgivings. I have no problem with the technology. The hand unit and controller must be "paired." The controller ignores everything else. The current science of "pairing" (or "binding" as the Radio Control industry calls it) is extremely sophisticated. And, the Prodigy RF has good reviews.
Rant if you must, but please back it up with your own investigative facts.
Meanwhile, I have registered a strong complaint to MB regarding the lack of the traditional brake controller wiring in the GLK.
3.5L
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Joined: Dec 2007
Posts: 898
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From: Woodstock, IL
His 2019 RAM Cummins Turbo Diesel Laramie; Her's 2007 ML320 CDI P3; Mine BMW R1200R
Thank goodness my only use for the tow hitch on the wife's GLK is for a 2 bicycle carrier. I would be much more livid than Venchka if I had to rewire a brand new Mercedes tow plug.
FYI, I just looked under it and the plug harness IS missing a few wires that my ML has for the same brand 7 pin plug.
FYI, I just looked under it and the plug harness IS missing a few wires that my ML has for the same brand 7 pin plug.
Thread Starter
Senior Member
Joined: Feb 2012
Posts: 296
Likes: 23
From: Central coast California
2024 GLC300, 2014 BMW M235i
Thank goodness my only use for the tow hitch on the wife's GLK is for a 2 bicycle carrier. I would be much more livid than Venchka if I had to rewire a brand new Mercedes tow plug.
FYI, I just looked under it and the plug harness IS missing a few wires that my ML has for the same brand 7 pin plug.
FYI, I just looked under it and the plug harness IS missing a few wires that my ML has for the same brand 7 pin plug.
Cheers,
3.5L
