howdy35

Hello. I have a 2010 GL450. Have decided to add the factory hitch. A search of the VIN indicated that the rear SAM was compatible, and inline with similarly topic'd posts, there are two spots available for a harness on the rear SAM.

I purchased the hitch from the dealer.
Included are:

Hitch
Stiffining bars
Bag of Bolts
Zip ties

I noted that there was no wiring harness, and after a week of the dealer(s) going back and forth, I was told to purchase a wiring harness.

So I purchased the harness part# A1644405834.

But something is wrong

The harness is about 16 feet long, and neither end matches the coupling on the hitch or the recepticles on the rear SAM. Is there some sort of bridge or connector adapter that I need? Anyone with any experience?

Thanks in advance

B

jimmyp

the harness is connected to the hitch its only a 12" pigtail to plug in to the sam, let me know if you need anything I did mine myself also.

howdy35

DId the harness come with the hitch or was it separate?

jimmyp

It was zip tied to it all conneted to the 7 pin connector, did yours have the 7 pin plug it should have, thats the one your trailer plugs into.

howdy35

I think Mercedes has recently changed the contents of the trailer hitch package.

Mine came with the trailer electrical receptacle mounted on the side of the hitch, but no harness.

So after dealing with 2 dealerships, it was only after I posted to a technician's forum, that I got the part number for the harness. Should be here tomorrow, so we'll see if it is right. Did you have your sam flashed at the dealership? I guess that would be the last step for me. If so, what did you pay?

partsguy95

When it comes to installing hitchs on ML'S n GL 'S
It can get tricky. Because the main harness's are all custom made to the vin#.

partsguy95

The harness u recived sounds like it goes to the front of the car. If that the case your car wasn't pre wired. That means taking all the seats n carpet out to do it.

howdy35

As I understand it, the harness I received was for a trailer brake. Don't need it

partsguy95

Could be a trailer brake harness.

partsguy95

I can check tommorw.

jimmyp

Mine came with the harness on my gl350 2010 when I got the hitch it has ywo plugs that go to the rear sam and a power wire just plugged it in and tested on my hitch and it worked fine with no dealer flash. Make sure you buy the led 7 pin plug if you have leds on your trailer. I can send you pics when you are ready for the plug locations

jayerinrodrigue

This is the part number of the hitch harness I ordered and it works fine. The only thing is I cant seem to get the interior trailer lights working but all exterior lights are fine. Had to get an load adapter from Curt to make the LED trailer lights work correctly.