trailer hitch questions
Thread Starter
Newbie
Joined: Sep 2010
Posts: 8
Likes: 0
From: newark ca
08 gl550
trailer hitch questions
Hey guys how you doing. I'm a newbie here and I just picked up an 08 gl550 couple days ago. The suv is an awesome machine and have couple questions about towing. My suv doesn't come with a towing package and I will need to install an aftermarket trailer receiver https://www.etrailer.com/Trailer-Hit...eID=2008308186. From the looks of the unit, it doesn't bolt in directly to the frame of the suv, but it "clamping" the frame. Im not towing a big load, a uhaul 6x12 enclosed trailer but i am towing it from the bay area ca to ucla. I was wondering if yall had any experience with this unit or is it better to find a oem trailer receiver from online
Super Member
Joined: Jul 2016
Posts: 705
Likes: 129
From: NE OHIO
1998 SL500,2011 GL550,2009 ML350,past 1995 E320 Cabrio ,2005 ML500,2006 ML500,1996 SL500,1972 280SEL
hitches
I have done both installed a factory and a lighter duty for a bicycle rack. I would get online at the big auto wrecking website and look around. Removing the bumper and installing a factory hitch is my suggestion. they are really beefy … next step will be how to wire it… can give you more details when you come to that
MBWorld Fanatic!
Joined: Sep 2005
Posts: 6,189
Likes: 242
From: Albuquerque
'10 CL550, '12 GL550
If you will be towing, without exception you should install the factory wiring harness for trailer lighting connection.
This isn't as simple as it sounds.
The factory harness plugs into the rear SAM, and in early days of X164 the rear SAM may or may not have been towing compatible. In those days, when a dealer installed the factory hitch and wiring, they also changed the rear SAM when required. SAM = signal acquisition module, a "scientific" sounding name for a box with a circuit board through which wiring to everything electrical passes. Rear SAM, for example, controls lighting, tailgate, rear wiper, trailer wiring (including braking), etc. This electronic wonder gets you things like bulb out warnings (even trailer bulbs) and detects a trailer attached and prevents the usual vehicle lowering that occurs at highway speeds to improve aerodynamics.
By 2008 it's possible all rear SAM were towing compatible. The rear SAM is behind interior paneling at right rear of vehicle. If hitch was factory fitted and possibly by 2008 even if not, there is wiring to the front footwell area for attachment of a trailer brake controller. Both the controller wiring and the hitch wiring will have yellow green plastic connector blocks where they plug into the SAM and at the front where you connect your controller. The connection sockets on the SAM itself will be surrounded by this same yellow green color ... this being how you tell by observing whether the sockets are present and you have a towing compatible SAM.
I write "by 2008" because I maintain both my and my granddaughter's 2007 GLs, one of which came with factory hitch and the other with that hitch retrofitted by dealer. Neither had the connector for trailer brake controller installed and I found the part number for that wiring harness and retrofitted both vehicles, rermoving/reinstalling much of the interiors to do so.
GL have CANbus electrical systems where vehicle wiring often carries messages to components along with power. It's how, for example, the system can detect a burned out tail light bulb and substitute a nearby brake light bulb, sending it a lower voltage. I suspect one could scotchlok in some trailer wiring but I'd say dash warnings would be likely and highway speed vehicle lowering would continue.
https://en.wikipedia.org/wiki/CAN_bus
This isn't as simple as it sounds.
The factory harness plugs into the rear SAM, and in early days of X164 the rear SAM may or may not have been towing compatible. In those days, when a dealer installed the factory hitch and wiring, they also changed the rear SAM when required. SAM = signal acquisition module, a "scientific" sounding name for a box with a circuit board through which wiring to everything electrical passes. Rear SAM, for example, controls lighting, tailgate, rear wiper, trailer wiring (including braking), etc. This electronic wonder gets you things like bulb out warnings (even trailer bulbs) and detects a trailer attached and prevents the usual vehicle lowering that occurs at highway speeds to improve aerodynamics.
By 2008 it's possible all rear SAM were towing compatible. The rear SAM is behind interior paneling at right rear of vehicle. If hitch was factory fitted and possibly by 2008 even if not, there is wiring to the front footwell area for attachment of a trailer brake controller. Both the controller wiring and the hitch wiring will have yellow green plastic connector blocks where they plug into the SAM and at the front where you connect your controller. The connection sockets on the SAM itself will be surrounded by this same yellow green color ... this being how you tell by observing whether the sockets are present and you have a towing compatible SAM.
I write "by 2008" because I maintain both my and my granddaughter's 2007 GLs, one of which came with factory hitch and the other with that hitch retrofitted by dealer. Neither had the connector for trailer brake controller installed and I found the part number for that wiring harness and retrofitted both vehicles, rermoving/reinstalling much of the interiors to do so.
GL have CANbus electrical systems where vehicle wiring often carries messages to components along with power. It's how, for example, the system can detect a burned out tail light bulb and substitute a nearby brake light bulb, sending it a lower voltage. I suspect one could scotchlok in some trailer wiring but I'd say dash warnings would be likely and highway speed vehicle lowering would continue.
https://en.wikipedia.org/wiki/CAN_bus
