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Yes, it means a factory installed trailer hitch. Not sure what you mean by computer integration. The Comand system will know you have hooked up a trailer when you insert the trailer lighting plug into the car's receptacle.
The factory trailer hitch package does not "add" a transmission cooler..
Interesting observation. I know that on my '13 Durango R/T there are a few line items that refer to towing, i.e., trailer sway damping, electronic stability control, heavy duty engine cooling, rear load leveling suspension. No mention of a tranny cooler. That got me thinking. I went thru the data card for our '14 ML350. Only ref to towing is trailer coupling. I went thru the OM and while there are many references to towing and the hitch, there didn't seem to be any mention of add'l cooling, etc as with the Durango. ESP mentions towing and how it may be able to help. But ESP seems to be standard, regardless of whether on not the vehicle is equipped with a factory hitch. Can we infer that MB provides a hitch as an option, but nothing else is added?
Interesting observation. I know that on my '13 Durango R/T there are a few line items that refer to towing, i.e., trailer sway damping, electronic stability control, heavy duty engine cooling, rear load leveling suspension. No mention of a tranny cooler. That got me thinking. I went thru the data card for our '14 ML350. Only ref to towing is trailer coupling. I went thru the OM and while there are many references to towing and the hitch, there didn't seem to be any mention of add'l cooling, etc as with the Durango. ESP mentions towing and how it may be able to help. But ESP seems to be standard, regardless of whether on not the vehicle is equipped with a factory hitch. Can we infer that MB provides a hitch as an option, but nothing else is added?
tow mode on my GL550 definately changes performance on it.
Day and Night stability.
no bouncing no sway.
Yes - with factory hitch system -when hooked up it adjusts/adapts the ESP both for better handling and for anti-sway - quite dramatic if you have trailer experience with non-MB vehicles - especially with lighter/smaller trailers - quite the Bomb !
Yes - with factory hitch system -when hooked up it adjusts/adapts the ESP both for better handling and for anti-sway - quite dramatic if you have trailer experience with non-MB vehicles - especially with lighter/smaller trailers - quite the Bomb !
Thanks. That is reassuring. Seems that the ML's driveline components are beefy enough not to need reinforcing.
That is the connector for the brake controller. Mercedes sells the other half of the plug and individual blade connectors to make the connection, if you are very particular and want to keep everything original. I was unable to find an aftermarket adapter plug for Mercedes.
See the attachment.
I used some slip on connectors to splice into the wires and left the factory plug in place. This is a simple job other than it is not the most comfortable part of the car to work in/on. I used an existing screw under the dash to mount the controller bracket.
On my vehicle, wires were:
Red 12V power
Brown Ground
Black/Red stripe Brake Light
Yellow/Red Stripe Brake Actuation
For the Primus IQ, in the 2017 GLS the wires mapped like this:
Unfortunately I did not have the time to do this myself. I did weeks of research and dealt very closely with the dealer on my install. I had to verify and re-verify that all the SAM updates were done correctly (took them two tries).
I am attaching a picture of the wire routing for you. If you need more help I can refer you to the best Mercedes tech ever. He will charge you $40 one time and he will answer ALL of your questions based on your specific VIN number. It was worth every penny for me.
I just purchased a 2015 GL350 to replace my 2006 ML500. I had to add the factory hitch to the ML and it was expensive, so I made sure this one had a factory hitch before I purchased it. The problem is I didn't check to see if it had a wiring harness!!! So I bought the harness from the dealer (they only sold me the harness for inside the truck, now I have the other harness on order). This routing diagram is the most helpful thing I've been able to find. I've torn the interior apart and laid the wires where they go, but I'm stuck. I need to know where in the fuse box, SAM, etc. the wires are plugged in. They're labeled things like: N10/B1-G CAV-35 3093. Using this routing diagram, I get that N10 is the SAM control unit, but I don't know where to plug the wire. Does anyone have access to the wiring diagram? I'd sure like to talk with the Mercedes tech Ericlojo referenced.
I'm still working on this. I now have both harnesses, but I still don't know where to plug the wires into the rear fuse box or the SAM control unit. Does anyone know of a way I can get a wiring diagram?
To give everyone an update, here's where I'm at. I've installed both wiring harnesses but found they don't connect together. Now my dealer thinks I need the "Trailer Recognition Control Unit". He said that 2016-up has this, but 2015 doesn't. So another $300+. I'll post the part numbers for both harnesses and the control unit when it gets here. Hopefully, the control unit will come with some wiring diagrams! Otherwise, I'll be back here begging for help.
Well, I finally got all the parts. I have a few questions regarding the wiring harness from the controller to the rest of the vehicle.
A. The hitch module/controller has 3 plugs. The RED coupling from the vehicle's wiring harness connects to one of the three plugs. The BLACK coupling from the hitch wiring harness connects to the 2nd plug of the controller. But, I can't figure out what goes on the 3rd plug of the hitch controller/module . According to the diagram I have, it is supposed to be a BLUE coupling (diagram below-22.4) which is also supposed of be part of the vehicle's wiring harness. Is there a BLUE coupling at all, or the 3rd plug on the hitch recognition module/controller remains unused/empty?
B. Also I came across 2 different wiring diagrams. One shows the Fuse box behind the passenger's side middle seat. Also it shows the brake controller wires passing under the passenger's seat and under the driver's seat, before ending under the driver's side under-pannel . The other diagram I found, shows the fuse box behind the driver's side back seat. Also it shows the brake controller wires passing under or through the dashboard. Do you remember which of the two methods you had to use? (My 2015 GL350 has the F4 Fusebox behind the driver's seat, yet I am not sure if the wiring diagram below (pic) is the correct one for the specific year/model.)
C. In the F4 fuse box, how many wires did you have to install, 5 plus the blue fuse holder OR 4 plus the blue fuse holder?
I received the harness from MB but it seemed to be a return so I am not sure if they send me the correct harness. (there are only 4 wires plus blue fuse holder, to install in the fuse box. (the wiring diagram I found online shows both the BLUE coupling for the hitch module and 5 wires plus blue fuse holder for the F4 fusebox - see pic below)
A. I searched, but I don't have any pictures of the connections to the trailer recognition module. I remember that once I figured out where the module was mounted, the rest of the wiring fell right into place. Sorry.
B. I never found the "Connection scheme" wiring diagram that you have. So I'm not sure about it. I used that other routing diagram you have. The rear fuse box (F4) is under the driver's side middle row of seats. X30/4 is under the passenger side rear door sill. I removed the glove box and a couple of panels to get to N10. I ran the Electric-Brake-Control connector over the trans tunnel behind the HVAC ductwork in the dash over to the driver's side. Once I had all the wiring in place, I had my dealer connect everything.
C. I can't remember how many wires there were for the rear fuse box (F4). I spent a bunch of time trying to figure out where they attach, I even made of copy of the fuse diagram that came in the fuse box, and tried labeling everything to match it up, but never could get anything close to clarity on where everything goes. Sorry.
Hello Yeffsy and Thank you for your reply and all your help.
I am exactly at the same position as you have been before finishing this complex project. Indeed there is no proper engineering information out there to help MB owners.
I am confused and unsure on how to proceed with the cabling.
I know I am asking too much, but since you have the same year/model as my car, and since access to the hitch recognition controller as well as the fuse box, is very easy, can you please please send me a pic of the hitch recognition controller and the fuse box of your car, so I can compare with mine. That will help me A LOT.
Again, I know I am asking too much but at this point you are the only hope I have to figure this out.
Thanking you in advance and wishing you a great day.
L-L
Hello Jeff. THANK YOU....I really appreciate your help.
Your pics show exactly what I wanted to know. Indeed fuse 126 is not used, as well as the third plug on the controller is not used.
I will go ahead with the installation this weekend and take it for programing next week.
Thanks for the tip on the AEM. I've been following this thread. I was really happy to see someone posted that their GL felt more powerful and they saw an increase of 2 MPG. Not exactly scientific study results, but good to hear!
Hello Jeff.
Indeed I noticed the same info regarding the mpg.
I am worried about a comment I noticed, by somebody that did the AEM, stating that the engine temperature increased after the AEM was done.
I mostly worried because I will be towing my camper, and I wasn't planning to immediately replace the radiator blower fan to the 850W one, that is needed with the towing pack.
I guess if I do the AEM, I will definitively have to go with the 850W fan 099-906-40-00 and also the rear encapsulation shield 166-520-05-23.
Of course I will use my ODB to record the engine temperature before and after the AEM is done, and then decide if I will go with the cooling parts right away or wait for later on (fyi $2200 for the OEM MB above parts without labor).
Wishing you a great weekend and thank you again for the pics and info.
LL
I tow a 26 ft sailboat. Loaded for a trip, I'm around 5000 lbs. I've taken a couple of short trips (80 miles & 110 miles) and got 16.8 MPG on both trips. I had an ML500 that got 15 MPG pulling the boat. I was hoping to get closer to 18 MPG with the deisel GL. Maybe after the AEM update I'll see an MGP increase while towing also. Fingers crossed!
So far I haven't had any cooling problems, but I haven't made trips in really hot weather yet. I have a cheap OBD reader that I can Bluetooth to my phone to monitor everything. If I do have trouble, I'll probably get a used fan from a wrecking yard. I've had good luck using www.car-part.com to search. That fan still isn't cheap. Currently, the lowest price is $475 from a yard in Denver.
I didn't know about needing the rear shield you mentioned. Where exactly does that go?
Hey Jeff,
I tow about 3700lb 21ft Travel Trailer (380lb tongue weight), and since it is way below the towing capacity of the GL, I was hoping that I could avoid upgrading the fan since the car will not pull at its max towing capacity. But with the AEM and possible temperature increase, (which honestly it sounds a little weird to be true) I might need to go for the 850W fan. I found an aftermarket for about $600.
In regards to the encapsulation shield 166-520-05-23, it basically allows more air to flow underneath the car, possibly to keep the temperature of the transmission or differential lower.
When I checked it online, it is exactly the same shape as the existing shield, except that it is missing some kind of fins (attached pics).
Also a vacuum line is needed (166-430-16-29) but honestly I am not sure yet which part is replacing and why. It is about $20 from BM. Maybe someone following this thread knows.
The second pic below, is the one used with the towing pack. I checked under my car, and I have the top one (the diagram one). Note the fins instead the circular shaped cuts.
Also, what is the tongue weight of your boat trailer loaded with the boat?
I've never measured my tongue weight. We seem to load the boat differently for every trip so I'm sure it varies. I'm also currently installing a new outboard that will change things again. I'll add checking it to my list of things to do after the new outboard is "finished".
Just finished the cabling...not as bad as I expected.
I tried the 7-pin tester I have but other than 12V on just 1 pin, nothing else seems to work.
I was expecting that the blinkers,lights and brake lights were going to work, but I guess either something went wrong or nothings works until programming is done.
Next week it is going for programming....so I will find out if my installation is correct or not.
L-L
If you're testing with a low voltage test light I doubt it will have enough resistance to recognize it. When I was testing my 7-way plug I got basically nothing. Tried it on the trailer I had, nothing. Then I read where LED lights don't have enough resistance for the system. Purchased a 7-way plug with a resistor in it specifically for this application and magic. Everything worked. Trailer lamps worked properly. Car recognized a trailer attached, etc.
Hitch Installation done today. It is not easy to get to the lower bolts behind the DEF tank and exhaust, yet with a lot of effort it is doable. I just had to lower the DEF tank about 3 inches.
@ Acetaylor: Thank you for your reply. I am using a regular $20 tester I got from Amazon...I used it when I installed a hitch on my Acura MDX and worked fine, but the MDX was pre-wired and I guess pre-programmed.
The problem I am facing now, it is with the bumper. It hits the hitch neck and the 7-pin plug mounting plate. I cut a pi shape off the bumper that goes around the hitch neck, yet the 7-pin plug mounting plate is on the way.
Hitch Installation done today. It is not easy to get to the lower bolts behind the DEF tank and exhaust, yet with a lot of effort it is doable. I just had to lower the DEF tank about 3 inches.
@ Acetaylor: Thank you for your reply. I am using a regular $20 tester I got from Amazon...I used it when I installed a hitch on my Acura MDX and worked fine, but the MDX was pre-wired and I guess pre-programmed.
The problem I am facing now, it is with the bumper. It hits the hitch neck and the 7-pin plug mounting plate. I cut a pi shape off the bumper that goes around the hitch neck, yet the 7-pin plug mounting plate is on the way.
Any ideas how to fix this issue?
Thank you
L-L
We are not supposed use the small cover. Are you taking about the full bumper cover?
There is no hitch removable cover on my 2015 GL350. It seems that I have to cut the bottom part of the bumper. I compared several pics of GLs, with and without factory hitch. It seems that the ones with factory hitch, have a circular cut. (see pics below) I guess I have no option but to cut it.
Do you guys have constant 12V at one pin of the 7-pin connector, even with the ignition OFF?
My wife is at work with our GL or I would include a photo, but to answer your question about cutting your bumper, yes you have to cut it out around the hitch and trailer plug connector.
If you haven't gotten an answer by tomorrow, I can also check my connector to see if one has power even with the ignition off.
This wiring diagram might be helpful. There's also way more information than you need on the Wikipedia page here. Looks like the upper right pin is supposed to be 12V. The wiki page says "via ignition lock" which leads me to believe that it's only on when the ignition is on, but ????
05-14-2017, 11:46 PM
