NOT MUCH LISTED ON THE M-B WEB SITE ABOUT TOWING WITH AN R500. I WOULD LIKE TO KNOW IF THERE IS A TOW OPTION AVAILABLE, WHAT IT MAY CONSIST OF, AND WHAT IS THE TOWING LIMIT? THANKS FOR ANY REPLYS.

 

My dealer says the R350 can tow 2500 pounds with an aftermarket hitch they can have installed for me. The R500 can tow more, but I forget how much.

 

There is a tow bar that's available now from Draw-tite, and one from hidden-hitch for both the 350 and the 500. Both are class III, and are rated up to 3500 pounds and 350 pounds tongue weight. I haven't been able to find a wiring kit in the US, but did find one in Germany. Luckily I have family in Germany who can send it to me. These parts may soon be available at the dealer. Meanwhile, a local trailer company can splice into the wiring for the tail lights to make it work.

 

So, I bet you never would have thought you could get sex at a MB dealer. When all was said and done, I got F-ed on this deal. When I bought the car, the stealer said he could have a hitch installed for about $250. The Hidden Hitch cost me about $125, and I installed it. It wasn't as easy as I'd have thought, but it went on okay after a long struggle. Took about two hours.

As I said before, I got a family member in Germany to get the wiring harness and send it to me. Plugged right in to the SAM and fuse box in the rear of the car, fit perfectly. But, didn't work. Half of the pins had +12v, all the time. I called the stealer who said it needed to be programmed in the computer and would cost about $50. Okay, fine. Well, two hours after I dropped it, they called asking if I had instructions with the harness. no. Two hours later they said it needed a new SAM for $300 plus the labor. Well... okay... this was gonna sting.

All said and done, after they installed the new SAM, that didn't work either. So, they tried to plug in the ML harness, since it looks the same. Didn't work. Then, they put the original SAM back in, plugged in the ML harness, and voila! We have a winning combination. So, I didnt' need the SAM, and really didn't need all that diagnosis either. Lesson learned the hard way is... get the wiring harness for an 07 ML, plug it into the fuse box and computer, and all should be golden. I have not yet towed with it... will probably take a test-tow later this evening and tow the snowmobiles to the gas station to fill up, just to make sure it all works well. So you know, that harness is $185 and doesn't include the 7-pin to 4-pin adapter. MB will charge another $30 for that, but you can get one at Home Depot for $7.

I think they should pay me now for letting them use my car to figure all this out. Sales manager says he will help offset some of this cost... we'll see what happens. The senior technician tells me that when I connect the trailer, the R should know it's there and will adjust the tranny, brakes, traction control, throttle response, everything to the right settings for a trailer. If the SAM doesn't tell the main computer, the adaptive qualities of the tranny and brakes will adjust within a few miles of starting to tow. Again, we'll see... but sometimes all those sophisticated electronics make things a lot harder than they need to be.

Now that I spent all this money setting it up to tow, and it took 8 months of my 27 month lease... I guess I will have no choice but to buy this thing at the end of the lease, or it won't feel like it was worth the effort! You should be able to learn from all I did to figure this out, and if you do it yourself, you can get the hitch and harness for about $300, and install it all in a few hours. Oh, and one other thing... they sold me (for $9) a bracket that holds the wiring harness connector next to the hitch. The bracket comes from the ML kit, and they used a few screws to attach to my hitch setup. You don't absolutely need this part, but it makes the installation look much more professional.

Good luck, and hop you enjoy your R Class!

 

By the way... anybody want to buy a german trailer wiring harness? lol

 

Sounder need some help on getting my r500 tow package working. Looking for plug from the Sam unit to the trailer plug.I know you said try a 07 ml wiring harness but I can't seem to locate a part number to order it from Mercedes. Can you help??? Desperate please contact me at 818 482-5877..Thank you,
Dave

 

This can probably be used for all '06 plus Mercedes Benz, as far as the towing wiring part...

I believe this kit and hitch can be used with all R350 up to '09.

Okay, I did it. The whole thing. Hitch and wiring.

Was it worth it? I'll tell you when I finish dealing with the pain...

Actually, IT WOULD HAVE BEEN EASY IF SOMEONE HAD PUT UP DETAILED INSTRUCTIONS.

So now I will...

What you will need...
Wiring:
http://www.towready.com/product/deta...19191&cat=1535

Four quick-splice connectors (Radio Shack 64-037)...two bags.
A box of 18-22 gauge butt connectors.
One 18 gauge eyelet (may need to buy a bag or box)
Small spool of 18 gauge wire (color doesn't matter)

Hitch:
http://www.etrailer.com/hitch-2006_M...-Benz_R350.htm
You can order both from eTrailer (there is a link when you order the hitch).
Both are fine, but the Draw-tite is always in stock and worth the $2 USA for that...

One M8 nut, one M5 nut, one M6 nut (optional).

The instructions for the hitch are actually good. Follow them with these hints:
1. Cut at least a 3cm notch out of the bumper cover. Yes, this seems a lot, but after three removals to trim, trust me. The hitch weighs a TON and you don't want to be lifting it more than once. Cut out the whole pan cover area that is recommended. I tried to go smaller and ended up cutting it out anyway.
2. The bolt holes have tight tolerances. You will have to work the loose bolts to get them to line up. Looking at the rear, I went with the floor pan right bolt first, two main bumper bolts, then the left floor pan bolt last. It was an arm-breaker, but it finally went in. If you have a non-crossbar version of the car, you are in luck. The kit comes with two plates that you add to the inside of the spare tire well and feed out through two removable rubber grommets. Since there is a LOT of play in these, this kit should go on easy (almost too easy). I believe the new and old deisel does not have the crossbars.

Wiring:

1. Remove the spare tire and vanity panels on both sides.
2. Use the double-stick tape on the back to mount the wiring adapter on the shelf to the left of the spare tire with the 4-prong trailer plug facing away from you. You can also use an M6 bolt to mount it to the many M6 tabs sticking out all over the shelf. I used both.
3. Open the wiring installation kit and crimp the yellow eyelet to one end of the fuse holder (cut the loop to do this).
4. Using the M8 bolt, mount the eyelet to the bottom bolt of the rear fuse box (this bolt actually feeds 12v constant to the rear of the car). Do NOT insert the fuse yet.
5. Using the yellow butt-connectors in the installation kit, connect half meter length of power wire (provided in the kit) to the other end of the fuse holder and crimp the other end to the power lead of the adapter. Tuck the wire under the vanity panel covering the rear air-conditioning tubes.
6. Twist the brown and white wires of the adapter together (tail light and ground), use the 18 gauge eyelet to ground it to the floor pan with the M5 bolt. There are many of these M5 stubs around as well.
7. The wires on the adapter to crimp to your light harness wires are too short. You will need to extend them to get to your light harnesses. 10cm should do it. Use the butt connectors to extend all but the green wire (it is long enough to reach to the right side of the car).
8. Remove the left and right panels that access your rear wiring harnesses. Unplug them both.
9. On both harnesses, there is an orange wire. This is the ground. You don't need this wire, but use it as a reference. The wire next to it is the turn signal wire for either side. The wire farthest away is the stop light wire.
10. Use the quick splice connectors to splice into the turn signal wire and stop light wire on the left, the turn signal wire on the right. You will need to cut away some of the cloth wrapping on the harness to get enough space to do this. These connectors seem too big, but they are small enough to splice the wire.
11. Connect the relevant wires to the quick splice connectors using the plugs provided. Run the green wire across the car, tuck it under the vanity panel you tucked the power wire under, and connect it to the quick splice connector on the right harness. Plug the light harnesses back into the tail lights.
12. At this point, you are ready to test. There is a LED testing plug that comes with the kit. Plug this onto the trailer end plug (has 3 LED lights). Put the fuse into the fuse holder (you will hear a slight click when you do this, as the adapter powers up...make sure fuse does not burn out and is intact), put the key in the car and flick the turn signal lever. You should see the relevant lights flashing on the LED tester. If this does not work, crimp the connectors harder (may not have spliced well).
13. You can route the trailer plug through a rubber grommet on the left of the car that is visible. This grommet is used to wire the rear motion sensors for the rear bumper. There is plenty of space to cut it and feed the plug through it (you need to remove it first, and be careful not to harm the rear sensor wires if you have them). I did not bother. I just drape it over the rear sill and close the gate on it.
14. Put all of the panels and vanity covers back on and you are done!!!

The wiring was the hardest, but only because I did not know what the wires were...

Total time: About 8 hours. If I had instructions? About 2.

Towed by 18 foot Maxum Boat today and had no issues!!!

Using these methods, there is no visible damage done to the car (not even to the harnesses. If you don't believe me, remove one of the crimps and take a look. Very small nick that is barely visible. You can remove the whole system in 5 minutes. If you use quick disconnects and velcro instead of butt connectors and the double stick tape, even faster. I plan on removing the entire wiring harness every time I take it in for major service. Should be very easy and quick. Panels are meant to be removed for access, so they are easy to get in and out. This is why I did not route outside using the gromet, but even a small slit is hard to detect. Why would they be looking?

I don't believe this voids your warranty. It would only matter if they were TRYING to find an excuse not to cover something, and I hope your service center is better than that. If it is not, then you need to find somewhere else.

Before I bought this wiring kit, I tried to discover the wires on the harnesses and set off the computer at least 10 times. It is very sensitive. This kit does not trip the computer, so it must be very gentle and is built precisely to be able to read the currents without tripping the computer.

Good Luck!!!

 

I read your instructions on getting a R-Class to tow with great interest. I too was told a hitch/wiring harness would be available within months of my purchasing my R-Class (Purchased in March of 2007), but it never happened. Based on your instructions I bought an 07 ML Class wiring harness and had it plugged in to the rear fusebox and computer on my 2007 R-320 4 Matic. Unfortunately it does not work. Could you let me know what Mercedes dealership you dealt with so I could have my dealership call them to get more technical information?

 

fixitsteve - thanks for the post! Using yours and one on "the other" site, I was able to install the Draw-Tite on my '07 R350 without any major issues. My tips would be:

- Cut 4cm
- Read the PDF on the other site for information about a "rib" inside the bumper cover that may need to be cut to clear the bar (I had to cut the rib).
- I used a floor jack to support the receiver end of the hitch, and a jack stand to support the other end (that attaches to where the cross-braces are).
- The only way I could make it fit was to install the cross-brace bolts VERY loosely first, then install the driver's side bumper bolt VERY loosely, then the passenger side bumper bolt. Then I tightened in a rotating pattern like would you use on lug nuts.
- I used a cutting wheel on my dremel to cut the bumper, and a new blade on a box cutter to cut the pan.

I am using this as a dog step (Great Dane), so I am not installing a wiring harness.

 

Thanks for the input! I'm sure it will help others that are doing this...its not easy...the hitch is quite heavy and you don't want to push it up there more than once.
4cm is definitely a good idea. I kept cutting, and cutting, and cutting. Had I just planned for more, it would have been easier. I can't remember the 'rib'. I wonder if this is 07 and newer?
Draw-tite needs to widen the holes just a 'tad' to make this easier. I think just a mm here and there would not have sacrificed the integrity and would have made this easier. They do a good job of making the holes long, but just too narrow. I actually thought of getting out my 1/2" drill and rolling it around in the holes prior to jacking it in place. Oh well...still holding strong.