When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Has anyone installed a hard wired trailer brake controller yet. I would like to know if the wiring on the GL is still available to connect to the controller wiring, like older models under the driver foot well? Also where to install the controller so that it does not interfere with the knee airbag deployment or cause any other potential issue. My 2014 ML has the controller under the dash above the driver footwell and can the 2020 models do the same? I don't like the wireless version brake controllers for several reasons. I will post the same thread on the GLE V167 forum as the results should be the same for both vehicles.
Has anyone installed a hard wired trailer brake controller yet. I would like to know if the wiring on the GL[S] is still available to connect to the controller wiring, like older models under the driver foot well? Also where to install the controller so that it does not interfere with the knee airbag deployment or cause any other potential issue. My 2014 ML has the controller under the dash above the driver footwell and can the 2020 models do the same? I don't like the wireless version brake controllers for several reasons. I will post the same thread on the GLE V167 forum as the results should be the same for both vehicles.
Here is the response from MBUSA. They actually answered a question! See attached instruction sheet.
"Thank you for your contact to MBUSA.
Review of records show your VIN has Code 550, hitch installed, therefore you would have the wiring needed for installation of an aftermarket brake controller. The dealership parts team should have the green connector/pins.
There will be a connector located near the trailer hitch where the trailer lighting and brake harness plugs into the vehicle.
I finally got my GLS the other day 363 days after I ordered it. I confirmed the wiring is there in the footwell for the Trailer Brake Controller and wired my Prodigy 2 exactly the same way as my ML350. Same color wires also. There is space for the controller in the footwell so it does not interfere with the knee airbag. The airbag is in the middle of the footwell and the panel covering the airbag is only approximately 10 inches wide so you can mount the controller to the right or left under the dash.
My current problem is there is no power running the the red wire with blue stripe from the GLS which powers the controller. I checked all the fuses designated for "trailer hitching" # 450, 452 453, 454 which are fine but there is one of the fuses #436 is missing the holder completely at location 436 in the rear cargo fuse panel - see pic of pencil pointing to where it should be. I don't know if this fuse is for the red wire with blue stripe. Maybe there is another issue? I also connected the GLS to my trailer and the lights work but no power to the brakes.
Does anyone have a hard wired brake controller connected to the GLS wiring under the dash? Do the euro models use that fuse #436 - maybe its for the electrically retractable hitch? I can't get an answer from my dealer because they are closed until further notice. The fuse holder at location 436 is not there - what is it for specifically?
Any GLS or GLE owners out there with the trailer hitch option that can tell me if they have a fuse in location 436 in the rear fuse compartment? Please specify if you are North American or Euro/UK spec. The electronic retractable hitch is not available in North America and may be the reason my Canadian GLS doesn't have a fuse in location 436. I don't have power to the Mercedes wiring provided for the Brake Controller and wonder if this is the reason.
Any GLS or GLE owners out there with the trailer hitch option that can tell me if they have a fuse in location 436 in the rear fuse compartment? Please specify if you are North American or Euro/UK spec. The electronic retractable hitch is not available in North America and may be the reason my Canadian GLS doesn't have a fuse in location 436. I don't have power to the Mercedes wiring provided for the Brake Controller and wonder if this is the reason.
I am interested in eventually adding a brake controller to mine as well, so I am following this thread. Unfortunately I can't help answer your specific question, but I would love to know the brand of brake controller you are using/recommend and why you wouldn't opt for a wireless option (pros/cons)?
I am interested in eventually adding a brake controller to mine as well, so I am following this thread. Unfortunately I can't help answer your specific question, but I would love to know the brand of brake controller you are using/recommend and why you wouldn't opt for a wireless option (pros/cons)?
Thanks!
Do you have the factory trailer hitch I think it is option code 550? Can you look in your fuse panel in the rear cargo area, RHS - indicated by the green + for the first aid kit and tell me if you have a fuse in location 436? The diagram is there in a slot above the fuse panel.
I have the Tekonsha Prodigy 2. The Prodigy 3 has some extra features I don't need. The Prodigy RF wireless one works from Bluetooth and is almost 4X the price, attaches to the trailer and can be stolen. I don't trust bluetooth as much as a hard wired device even with the failsafe system. The wireless controller also has a hand held which plugs into the 12V cigar lighter and I already have a splitter on that power source for my trailer backup camera and trailer Tire Pressure Monitor System and 3 plugs would not be workable. The Curt brand wireless system would hang down too low from the 7 pin connector and can easily be damaged.
Any GLS or GLE owners out there with the trailer hitch option that can tell me if they have a fuse in location 436 in the rear fuse compartment? Please specify if you are North American or Euro/UK spec. The electronic retractable hitch is not available in North America and may be the reason my Canadian GLS doesn't have a fuse in location 436. I don't have power to the Mercedes wiring provided for the Brake Controller and wonder if this is the reason.
I have the factory hitch, and there is no fuse in that location.
Do you have the factory trailer hitch I think it is option code 550? Can you look in your fuse panel in the rear cargo area, RHS - indicated by the green + for the first aid kit and tell me if you have a fuse in location 436? The diagram is there in a slot above the fuse panel.
I have the Tekonsha Prodigy 2. The Prodigy 3 has some extra features I don't need. The Prodigy RF wireless one works from Bluetooth and is almost 4X the price, attaches to the trailer and can be stolen. I don't trust bluetooth as much as a hard wired device even with the failsafe system. The wireless controller also has a hand held which plugs into the 12V cigar lighter and I already have a splitter on that power source for my trailer backup camera and trailer Tire Pressure Monitor System and 3 plugs would not be workable. The Curt brand wireless system would hang down too low from the 7 pin connector and can easily be damaged.
I do have the trailer package on the GLS 450. 436 for me looks like yours, but I don't have a fuse in location 450 (just in the other 3 out of the 5). Not sure if that helps or did I open up a can of something now...
I do have the trailer package on the GLS 450. 436 for me looks like yours, but I don't have a fuse in location 450 (just in the other 3 out of the 5). Not sure if that helps or did I open up a can of something now...
Thank you . Are you in the United States? You spotted that missing fuse too - I put one in 450 too but it didn't get power to the brake controller wire.
Thank you . Are you in the United States? You spotted that missing fuse too - I put one in 450 too but it didn't get power to the brake controller wire.
Yes, Atlanta suburbs.
What size fuse would even fit in 436? It’s tiny...
I have an aftermarket Stealth hitch system on 2020 GLE 350. Have a Tekonsha Prodigy RF brake controller on my Trailer. F-150 was used to initialize/pair the brake controller. The installer said Tekonsha's don't like to get paired on German cars. But finally had it up and running.
For an SUV that is capable of towing over 7,000lbs I’m disappointed that there is no integrated brake controller option. The integrated solutions look much nicer. I cringed when I had to drill holes in my lower panel to mount mine. Mercedes please add this as an option!
For an SUV that is capable of towing over 7,000lbs I’m disappointed that there is no integrated brake controller option. The integrated solutions look much nicer. I cringed when I had to drill holes in my lower panel to mount mine. Mercedes please add this as an option!
Did you get power from the from the Factory plug under the dash? I assume you also have X167. I cannot get power or brake signal from the Mercedes 4 pin plug under the dash. It is the same 4 pin plug as my old W166 and that had power immediately. Did you have to do something other than connecting the wires to get it to work? I put a fuse in position 450 but that did nothing. Waiting for an opportunity to take it to the dealer but it sure would be nice to get it working now so I can tow.
For anyone following this thread I now have my hard wired Tekonsha Prodigy 2 brake controller working. I took it to the dealer this week because I could not get power from the factory 4 pin plug under the dash for the brake controller. Despite my prior checking of fuses the dealer told me the problem was just a blown fuse. Bottom line you can use the 4 pin plug in the 167 like the 166 version before. One thing about the X167 it works differently than the W166.
I took my Tekonsha P2 trailer Brake controller out of a 2014 Mercedes ML350 and put it in a 2020 Mercedes GLS580. I also discovered the red wire does not get power when the brake is applied on the GLS580 unless the 7 pin trailer plug is connected. That was not the case with the ML350 which always woke up the P2 when the brake pedal was pushed, trailer connected or not. The GLS580 does not wake up the P2 unless the trailer is connected or the manual brake lever is activated. FYI on Mercedes the factory wires supplied under the dash for the brake controller the brake (red) wire from the controller connects to the black wire with red stripe from the factory plug and must be connected to the trailer to get power.
Last edited by marchgroupinc; Jun 18, 2020 at 08:29 AM.
Reason: new additional info.
I have installed P2 brake controller to my 2012 GL350 through the existing green color connector under the driver side panel to the controller using the harness I bought for my specific requirements (P2 controller to MB can be purchased from trailer supply on line for about $12). I have logged over 20,000 miles on this set up including 8500 miles road trip to ALASKA our Airstream.
Just purchase GLS580 to be delivered this week. Already purchased the connecting harness and ready to hook up the existing P2 to my new car.
I am using Velcro to install the controller under the dash and remove it when not in use.
Also what I read on Forum is that you do not get power to the controller unless the car is hooked to the trailer via 7 pin connector.
What I wrote above is to the best of my knowledge and fact, however, I could be wrong which will not be the first time
Please stay safe, wear mask
Cheers
I have a 2020 GLS 580 and cannot find the plug area for the brake control in the driver footwell area. Does anyone have a photo of it from this exact year and model?
Very frustrating! Appreciate any help so I can hookup my P2 trailer brake controller.
I have a 2020 GLS 580 and cannot find the plug area for the brake control in the driver footwell area. Does anyone have a photo of it from this exact year and model?
Very frustrating! Appreciate any help so I can hookup my P2 trailer brake controller.
Thanks
I have the same controller and 2020 GLS580. Here is a picture. You might have to look around more to find it but it is there if you have the trailer tow hitch package. It has been a while but i think it was up near the top of the carpeted area. look for the red ,yellow, black with red stripe, and green wires. I hooked up my P2 without the plug, just cut it off and wire the P2 harness directly. If you don't want to do that there is an adapter plug available - same as previous years for all Mercedes. Here is a link for the adapter for Amazon Canada - your profile doesn't state what country you are from but Amazon may have it in other countries too.
I have the same controller and 2020 GLS580. Here is a picture. You might have to look around more to find it but it is there if you have the trailer tow hitch package. It has been a while but i think it was up near the top of the carpeted area. look for the red ,yellow, black with red stripe, and green wires. I hooked up my P2 without the plug, just cut it off and wire the P2 harness directly. If you don't want to do that there is an adapter plug available - same as previous years for all Mercedes. Here is a link for the adapter for Amazon Canada - your profile doesn't state what country you are from but Amazon may have it in other countries too.
The plug was tucked in above and I pulled it down Controller set back from air bag panel
Wow. Thank you so much for the photos, information and link to the harness. I just bought it and will check again tomorrow for the wires in the footwell. Incredibly helpful!
With the help of my neighbor I was able to locate the famous green plug under the dash board.
1) Remove the panel behind knee airbag held by two crews (power head)
2) Remove plastic piece which runs from the door bottom sill and rap around the side of the wheel well.(it is one piece held by clips and rubber liner)
3) Look under the dash, the green plug is buried under there.
I bought the connector from Trailer Inc for the Mercedes and P3 controller
Good luck I hope my explanation is clear enough.
My issue is when I connected the Airstream trailer there was no power to the trailer e.g. brake, running and turn signal light.
Tomorrow I will purchase the Vehicle Trailer Wiring 7 Pin Tester to make sure my Mercedes is providing the power
Any advice will be appreciated.
CHEERS stay safe
With the help of my neighbor I was able to locate the famous green plug under the dash board.
1) Remove the panel behind knee airbag held by two crews (power head)
2) Remove plastic piece which runs from the door bottom sill and rap around the side of the wheel well.(it is one piece held by clips and rubber liner)
3) Look under the dash, the green plug is buried under there.
I bought the connector from Trailer Inc for the Mercedes and P3 controller
Good luck I hope my explanation is clear enough.
My issue is when I connected the Airstream trailer there was no power to the trailer e.g. brake, running and turn signal light.
Tomorrow I will purchase the Vehicle Trailer Wiring 7 Pin Tester to make sure my Mercedes is providing the power
Any advice will be appreciated.
CHEERS stay safe
I find the 7 pin plug on the Mercedes is at a bad angle and sometimes it does not connect. To confirm the plug is inserted fully make sure the plug is pushed all the way in and the hook on the Mercedes 7 pin door cover catches on the protrusion on the trailer plug that stops it from slipping out. My Airstream plug is just long enough to plug into the Mercedes and allow the minimum slack to make turns without straining the plug. I remenber I had to pull all the slack availble on the trailer plug wire to get it to connect.
Also note the Mercedes has to be running or at position 2 of the start button to activate the trailer lights. Another issue for we was discovering the power to the brake controller is not activated (it is in sleep mode) until you connect the trailer or manually activate the brake controller. When you shut the engine off the brake controller stays on for a few minutes until it goes into "sleep mode".
Good luck finding your problem. My GLS and 25' Airstream
Thanks for the input, yes the engine was on still the lights on the trailer were not on. Today I will check the power output of the GLS580 trailer 7 pin plug.
Also I noticed that the GLS is lower by an inch from my previous 2012 GL350, assuming when trailer hooked up the level automatically goes to normal height.
Will get the hitch modified to increase the ball height.
Thanks for all the responses.
Cheers and stay safe
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
Brake controller for 2020 Mercedes GLS580
