Towing Question
 

Looking for some towing stories and advice. We have a 2012 ML350 Bluetec. According to the owners manual and a call to MBUSA, the towing capacity of the ML350 Bluetec is 7200 lbs with a 575 lb tongue/hitch weight. Fairly impressive although the tongue weight is a little low, but I digress. Anyway we are planning on towing a Keystone Outback Ultra Light 210URS travel Trailer. it is 23 feet long, weighs 6500 lbs (Fully loaded) and has a hitch weight of 485 lbs.

So, the trailer is well within the capabilities of the vehicle. Problem is the ML350 did not come with a tow hitch, etc. I have sourced a very nice hitch from E-trailer.com, and also the MB OEM stuff. Has anyone put on a tow hitch and wiring system (plus trailer brake set up) on an ML350?

Thanks in advance for any tips and advice.

will uhaul do it for you?

Most hitch companies post car specific hitch install instructions on line, that would be a good place to start.

Some cars are wired for trailer brakes and you just plug the controller in under the dash. Some are prewired for trailer lights requiring only a socket or a jumper harness.

I would highly recommend doing the factory hitch kit. There are software adjustments to the Powertrain operation that are engaged when you plug in the trailer lights. This would not occur with a 3rd party hitch.

Also the way they do rear lights on the newer Mercedes you will have a heck of a time just tapping in. They use LEDs with pulse width modulation, which is totally incompatible with regular bulbs. The way they do the trailer lights on the newer model is to provide a separate controller that is just fed with 12 V and the CAN bus signals, and it derives its own lighting signals independently of the vehicle lights.

I looked into doing this for our 2014 ML350, it is about $1500 in parts and you have to take half the interior apart to run the harnesses. But mechanically it bolts right in. You will also need Xentry to version code the rear SAM to accept the hitching mechanism controller. I think this can be done with a bootleg Xentry.

Also with a trailer that heavy you will need a brake controller.

We have a 2008 ML320 that has a factory hitch. It has the 7 pin connector and there is a plug up under the dash that you can buy a dealer harness for that accepts a 3rd party electric brake controller for the trailer brakes. I have only pulled lightweight trailers with this vehicle so I never retrofitted it for electric brake.

I did have to get a special 7 pin to 4 pin adapter that has compensation resistors for LED trailer lights for the ML320. The trailer outputs were expecting incandescent bulbs and they were absolutely driven crazy by LEDs. Got a ton of error messages on the dash about faulty trailer lights until I used the magic plug. I got this from e trailer dot com.