I know there are many threads already on this topic but all are very vague and without any solid info. I wanted to start a thread that would detail the installation of an OEM trailer hitch on the GL model X166 with detailed instruction and helpful information for anyone actually interested in taking on this project on their own. In this thread please lets assume that an OEM trailer hitch installation is the way to go so please limit your comments and opinion on aftermarket units.

From obtaining my own quote and from what I have read others were quoted by MB dealers you will be charged anywhere from $1600 - $2500 for parts and labor.

Through the input of others, I hope that this thread will provide valuable information for anyone interested in doing the installation on their own and saving some money.

From my research here is what I have found out so far:
- Bumper cover needs to come off to accomplish the installation
- parts needed:
A) Trailer Hitch part #166-310-11-37
B) stiff bars (support bars) - Don't know the part #
C) Wiring Harness - don't know part number
D) Foam cover (bumper protector)
E) Rear SAM (i am not sure if this needs to be upgraded)
F) Trailer brake controller (aftermarket application works best)

Info I still need:
1) Wiring diagram. where does the wiring harness actually plug into?
2) Rear SAM. Does it or does it not need to be replaced/upgraded on the x166? I see conflicting info here. Some say that after 2009 model GLs the SAM is powerful enough and does not need updating but prior to 2009 it needs to be replaced. My understanding is that having the SAM connected to the wiring harness will give you trailer stability control (just like factory installation)
3) Part #2469005501 - Trailer Control Module. is this the SAM? Do i need this part for the installation?
4) Does the SAM need to be programmed by the dealer after the installation?
5) does a factory installed hitch have any other towing options upgraded? like heavy duty oil cooler or transmission cooler?
6) Is the new vehicle and/or extended Warrant void if you do your own installation?

 

Yes - either a OE hitch, or aftermarket hitch - can be added to a X166 - but exactly what electrical/integration features you will have - or not have - depend on yr/model - and whether you have MB integration (SAM + COMAND + controller) or aftermarket integration (No SAM + No COMAND + maybe no wired controller/wireless only)

1) From SAM + COMAND standpoint - all years X166 are NOT the same when adding rear mounted hitch. With your VIN# - your dealer parts dept can advise you whether new SAM is required or not. Off the top of my head 13 needs SAM - 14?/15/16 might not.

2) Depending your your yr X166 - Mercedes has a "hitch kit" which contains OE hitch and wiring harness for hitch electrical - for those yrs/models where SAM adapts itself no SAM change - for other year SAM needs change out if you want integration - and yes the wiring is a pain - since requires electrical connection up to battery for correct integration. However, I don't "think" wired brake controller gets added with this kit AND kit hookup instructions are Star database only and kit does NOT come with printed electrical hookup instructions.

3) Check Curt manufacturing website - I believe they will have a website install video for tip X166 hitch - this is the mechanical part - and they have full parts breakout for their aftermarket hitch. If you just need basic wire hookup - with a Mudulite + splices is all you need.

4) Brake controller - heck, if you don't have wired adapter in the front - most are going to wireless or OBD connected wireless anyway.

Good luck - research on your specific yr/model with dealer parts is the best thing.

Yes - Mercedes does not want to add more liability with dealer mounted hitches - they take liability with the factory mounted hitch - can't blame them for not sticking their pee-pee out further really....

 

assuming i do not want/need the brake controller. I do however want to connect the wiring properly. Where is the rear SAM located? is it in the bumper? under the 2nd row seats?

 

Hey GLr

I just purchased a 2014 GL, it was a stellar deal, but for some stupid reason it was a special order with everything but the trailer hitch. Did you continue research on this? What did you find? My dealer gave me a quote for "factory quality" hitch install but I am not 100% sold that they will do all the proper wiring, and what wiring is really necessary. Any more info you found would be greatly appreciated.

 

The info is this ... in another thread you say you have Active Curve....

1) Go to Curt mfg web site and you can cross reference their hitch for your MB - and download pdf install instructions for the mechanical hitch and/or they might have video of the install as well.

2) For Curt hitch - with basic wiring hookup - you can quote with a U-Haul outlet - basic wiring is brakes/lights/etc that uses a Modulite relay. "Usally" around $450/can-be-less.

3) With VIN# you can have your MB dealer quote you hitch - for your year it "could be" hitch + factory wiring harness as a package - they will advise you if you want/need a update SAM rear module or if your existing SAM will convert over using factory wiring. This is parts quote only. That can be between $900-$1600 depending on what parts are required.

4) You can have MB Service quote the dealer install - if adding factory harness - with or without changing Plug-N-Play SAM - shop hours "should be" between 5-6hrs.

Whether it's a aftermarket hitch w/basic wiring or for your tow needs you require factory hitch w/factory wiring harness - that decision is up to you..

 

I've contacted multiple MB service departments regarding the hitch installation. From the information I have been given I am not confident that the dealers really know what needs to be done and whether the rear SAM needs to be upgraded or not. I have gotten quotes from $1600 to $3400 and in between. No service advisor was able to give me a straight answer as to what parts or work actually needs to be done to have the hitch installed to factory standards. When I asked about the rear SAM I was told by two dealers that they are not sure as they don't have any notes in their service portal about the SAM.

I started looking on Ebay for OEM hitches and found what i needed. I bought an OEM hitch along with a wiring harness and frame installation brackets. The parts are sitting in my garage and have yet to decide who to use to get the hitch installed....

the aftermarket hitch installation just looks like crap. i have not found one that does not stick out from under the bumper