I have a new 07 320 cdi, I want to put a trailer hitch on it. The hitch is no problem, I assume an 07 ml 350 hitch will work. However the wiring worries me, the dealer says I need a computer package, to properly control the lights. I wonder if 1 of these universal tie-in systems will work? I see where there are some that keep the vehicle and trailer isolated, does anyone have any input? I am only towing a fishing boat, so running lights, signals, and brakes. Thanks in advance, Brian

 

here is what i did for ml320 2001. i bought aftermarket hitch that bolts directly to frame. i think it was like hitches direct.com or something like that. it cost about 100 bucks. you have to remove bumper. easy. i was told like you were told that you need this or that. my trailer has simple 4 wire set up. so i bought 4 foot plug/wire that plugs into trailer plug. i hooked up directly to car right behind where special mercedes wiring harness plugs in with those items that let you splice in without cutting wire. i just used test light and helper to figure out which wire was ground, right, left, and brakes. you will have to figure out where everything is for your vehicle. i was told i would blow fuses, or it would not be enough power, etc. i think it is fine as there is no power brakes.

 

OK, this is an old thread. Still active? I am a new member. Hope I am doing this right.

I would like to install a trailer hitch on my ML320 (2000). I found the hitch that bolts on the frame. It's straightforward. But ... (1) Where can I find instructions on how to remove the bumper? It's supposed to be easy. (2) A special wire harness by Mercedes was mentioned (on this thread and another that I came across earlier but now don't seem to be able to find again). I called Mercedes, Parts Department at our local dealer. I was told they didn't have it and I'd have to buy it at some supply store ... ? Any info that would be helpful to purchase this wire harness? I only see a plug next to the place at the frame where the hitch is mounted. It looks like a 12 V cigarette lighter receptacle, except a little bit bigger in diameter, with apparently only two wires going to it. Is this already the magical wire harness? Is wiring the harness if needed difficult?

 

First, bumper cover is removed by removing 4 screws behind (small side and big center covers) on the bumper.
Wiring harness for W163 with 3 inbound plugs is part no. Q-6-54-0013
Wires in left rear cargo compartment next to fuel tank filler neck is:
Green = L turn signal
Pink = R turn signal
Gray = backup lamp
Red = power (+12V from fuse #18)
White = tail lamp
Orange = stop lamp (and brake control)
Brown = ground (negative from chassis)
Hope this helps you out. I post this info before on this forum.
Bernard

 

Hi Bernard,
This was so very helpful! Thanks!
Sorry for apparently having overlooked your earlier posting.
Best,
Bertram

 

Hi Bernard,

Sorry for bothering you again. I have several questions. (1) Structural: I saw instructions that asked for braces to the frame on the left and right of the rear of the car in addition to the four-hole hitch (class III) that I purchased. Are these needed? I only saw them referred to once. (2) Electrical: In addition to the harness, do I need the bracket which holds the electrical socket AND the socket itself? Do you know the part numbers for those? (3) It seems that these parts are impossible to get. Are there any alternatives? I saw a number of references by people that made their own sockets and harnesses. But honestly, I'd rather avoid that.

Thanks for your help again.

Bertram

 

Hi Bertram,
You don't need the same socket that comes with original wiring harness. I have it but I have to use an adapter to convert the mercedes round plug to flat 5 wire outlet that most trailers that I use needs. The frame support brackets are there to help the frame corner welds, I'm not sure what are you trying to haul with your ML but the frame on it is so strong (it is dual ply like pipe inside of a nother pipe). I always think safety first and I don't want to give anyone wrong advice but those corner supports will not do much since the are 3mm thick bent sheet metal. You could fabricate them if you are handy enough, I made some drawings before I installed the original oem Oris harware kit.
Kit is part # 0107.2235.910.
If you have aftermarket receiver, I would buy good grade 10.9 four main screws, M14x1.5thread 55 mm long fully threaded, tightening torque 118 ftlbs or 160Nm.
Bracket for outside plug is part # Q-6-54-0033
Pollak outside plug is part # Q-6-54-0015
Im not sure about part # for corner brace but spacers for them are 163 315 00 22, so if you find these, they should be starting 163 315 XX XX.
I have the oem installation instructions with nice pictures, if you need it.
I have also contacted Oris about this hitch assembly, they could ship them from Germany where they made them but shipping cost would be very expensive.
Regards,
Bernard

 

Hi Bernard,

Once again, you have been very generous with your help and with great expertise!

Thank you so much! It's all worked out beautifully!

Bertram