Trailer wiring help for a W210 wagon?
 

Hi, I purchased a detachable Bosal towbar while I was in Europe last week, along with all the electrical wiring and 7-pin plug outlet, also got the 7-pin male end to wire onto my trailer as US style is different with only 3-pins, seems to be for brakes only.

I installed the towbar yesterday and wanna do the electricals soon as well. The Bosal dealer told me there should be a plug in the trunk of my MB, which he normally sells an adapter for but he couldn't get it in time before I had to come back to the States. He told me to just vampire clip the trailer wiring to the wire coming off this plug in my trunk. Ploblem is I have yet to find this plug (tho I'm sure its there) and even when I do I don't know what pin or color is for what. I really want to avoid the ghetto method of tapping into my tail lights as I'm sure it will trigger the "lamp malfunction" warning that is so annoying on the late model W210's.

Any chance a someone has the pin out or schematic to the tailer wiring plug? Really looking forward to towing my race bike instead of begging friends to borrow their pick up truck! :D

See attachment

Note that "3 pins" isn't enough, as it has to be at least 4
taillights
left signal/brake
right signal/brake
ground

The euro wire harness does NOT combine turn signals and brake, just as they aren't combined on your car. You'll either need to change trailer lights or fit an additional "converter" to use your current trailer light system.

euro 7 pins

taillights
brake lights
left signal
right signal
backup lights
rear fog
ground