My vehicle is a 2010 ML350 w/o a trailer hitch. I'm trying to add a factory trailer hitch. I've be having a very tough time finding the part number of the relay circled in the picture below. I've scoured the internet and talked to a dealer, but no luck.


Relay L (pictured below)

Valid for code (550) Trailer hitch:– Trailer circuit 30X relay (F4kL)
Is there anyone who knows the part number or can look at their vehicle and share the part number? I really appreciate the help.

 

If memory serve me correct, an entirely different SAM is needed.
But I could be full of poop.
Just go with an aftermarket setup.
That's what we did. If you get any errors on tail lights after install, clean the contacts on the bulbs
and housings, and all will be well.

 

My understanding is the same as yours about the rear SAM. The image is of the rear fuse block. The SAM is located under the right rear seat in the 2010 ML350. Thanks.

 

Take a look at this thread: https://mbworld.org/forums/gl-class-...tched-12v.html

The relay is for trailer 12v accessory power. Not needed if you don't have accessories on your trailer.

OP has a 2010, which already has the correct SAM. Only 06, maybe up to 08 need the new version of the rear SAM. Beyond that, it is simply coding the car to recognize the trailer.

One of the most important things you lose out on by going aftermarket is the trailer sway control. There are also other options you may or may not miss out on depending on what your car comes with.

 

Thanks for the reply. I looked at that thread and the relay that the posted mentioned that did not work (A0025421119) is the number that I settled on, although now replace by (002-542-92-19).

Everything I've found indicated that I needed a new rear SAM. I thought it was the same number (A1649005101) as posted in the thread.

Here is what I currently have.
Rear SAM is a A164 900 67 00
I looked under dash the near the ODB2 connector and could not find a green connector tape to it for electric brake control.

Here is what I think I need in addition to the hitch.
164-900-54-01 Exchange Control Unit (for trailer support) $364.30
00164-440-15-39 Cable Harness. (trailer harness) $64.80
Product ID: 164-440-25-13. Wiring Harness (to provide length to reach rear SAM and Green plug under dash) $54.00
Product ID: 002-542-81-19 U slot relay $15.38
Product ID: 002-542-92-19. L slot relay $13.53

Does this seem right?

 

Looked up your SAM part number and you're right, it does not look like it has the connector for trailers. Yes, you will need a new SAM in order to enable OEM trailer functionality. If you check the link I posted, there's a picture of the SAM. You need the version with connectors in the A slot. Yours is blanked off in the A slot.

Everything else looks correct, though can't be 100% certain on the wiring harness. No pictures of it available on the internet to tell what is actually there.

 

I gave up on this and just went aftermarket. Very interested to see if someone can get an existing SAM to work or recoded. I have a 2011 RWD. I bought the OEM wiring harness but never used it because all threads led to buying a new SAM.

 

As I posted above, only if you have a SAM with the pins in connector A. Some versions of the SAM will have that connector blanked out.

The rear SAM in my R500 was replaced by the previous owner for some reason and fortunately it had the populated A connector. All I needed to do was jump into Xentry and enable trailer recognition in the central gateway and rear SAM.

In one of the W251 threads, it mentioned that W251s newer than 2009 had the SAM with the A connector. Couldn't find much other threads to corroborate that though. Clearly W164 did not come standard with the SAM for trailer connectivity since OP's 2010 did not have it.