brake controller and wiring for 2011 GL550
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GL550
brake controller and wiring for 2011 GL550
Has anyone installed a brake controller on a similar model and year? For a box trailer with electronic brakes and LED lights. If so, can you send me info on where to install needed wiring or parts. My vehicle does come equipped with an OEM towing package. but no one seems to know how to wire the vehicle so the running lights, brake lights, turns signals and electronic brakes will go on by plugging in the 7 plug vehicle side connector. 
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2021 V167
Canvas
Even though your trailer has led lights you may need a plug in led converter to get the trailer recognized by the GL. My 2011 350 would not recognize my Airstream with led lights without it.
Good tow vehicle.
Good tow vehicle.
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GL550
'thank you KrustyKustom for the heads up!!"... thing is i really fail to believe not one person in this hole country is 'NOT' hauling a toy-hauler or a utility trailer with a Mercedes SUV and has been or going through the same BS I'm going through just to make my toy-hauler work correctly 
u dig..?
u dig..?
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GL550
lets start with the green connector under the dash. a shop who instals break controllers was attempting to install one on my 2011 GL550. they couldn't figure out why all the wires in that green connector all did what they were suppose to do except for one which was a purplish wine colored wire, its function is suppose to go live when the break is applied on the vehicle. (next prob.) I had a single axle flatbed trailer which had only a 4flat connector trailer adapter, with no electronic breaks. all the break lights ,turn signals would go on no prob. but now that i just purchased a 2014 LOOK trailer. its a 7X14 inclosed with LED lights & electronic brakes, dual axle, which has a 7way trailer connector. nothing will go on when I connect it to the GL, no brake lights, no running lights, no turn signals, no emergency. Even if the brake controller is not installed at this point, everything else should still go on. I took it to a Mercedes dealership and they said they reprogrammed the rear SAM and I tried connecting it again but its still the same. nothing works i even tried taking it back to the installation shop & they said the purplish wire was still inactive... I'm at a loss on what to do next. i'm almost at the point of considering a after market wiring on the vehicle. any suggestions or where I can have this problem resolved anyone?
Last edited by Living Canvas; Mar 28, 2014 at 04:47 AM.
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Out Of Control!!
Joined: Aug 2010
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From: Charlotte NC area
2019 WS222 S450 4-Matic / 2007 W211 E350 4Matic (Sold) / 2008 X164 GL320 CDI
I don't see a "Purplish" wire in the list.
Maybe it is the Brown wire which is the ground (so if they think it is the brake switch line, of course it does not work.)
The other issue could be that if your trailer has LED lights it might not pull enough current to tell the GL that the trailer is connected.
Test it with a known good trailer with non-led lights, or get a trailer connector and wire up some lights to make a test set.
You may have to add resistors to your trailer to make it work.
I think your problem is with the person doing the install and testing, not the GL.
Where are you? Maybe find a trailer shop that has done an MB.
Maybe it is the Brown wire which is the ground (so if they think it is the brake switch line, of course it does not work.)
The other issue could be that if your trailer has LED lights it might not pull enough current to tell the GL that the trailer is connected.
Test it with a known good trailer with non-led lights, or get a trailer connector and wire up some lights to make a test set.
You may have to add resistors to your trailer to make it work.
I think your problem is with the person doing the install and testing, not the GL.
Where are you? Maybe find a trailer shop that has done an MB.
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Out Of Control!!
Joined: Aug 2010
Posts: 12,517
Likes: 628
From: Charlotte NC area
2019 WS222 S450 4-Matic / 2007 W211 E350 4Matic (Sold) / 2008 X164 GL320 CDI
If you can't find someone you trust that has done this before, I would start at the beginning and check all the wiring.
Unless a wire is broken inside the car, or the SAM is bad, the whole system is fairly simple and easy to put in.
Unless a wire is broken inside the car, or the SAM is bad, the whole system is fairly simple and easy to put in.
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GL550
thank you all for your help i really do appreciate it, i found the answer: all european vehicles need a 7 to 7 pin converter adapter if your trailer has LED lights , but if your trailer has reg bulbs all around it will recognize it and the vehicle will do what its suppose to do. here's a link to who ever has a similar prob.http://www.etrailer.com/Wiring/Tow-Ready/20142.html
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2021 V167
Canvas..
You got it now, that's what I was sayin earlier is without that adaptor the GL Sam unit does not recognize the trailer, without break lights you do not get the signal for brake controller. Seems crazy but the Led adaptor works perfect.
