I have a R350 (2007) and a pop up camper that has electric brakes.
I upgraded the SAM ($418) and got the ML-class A 164 440 15 39 harness. I installed the SAM but are not sure where to plug the harness into?
The ML-class A 164 440 15 39 harness has the following wires.
1) White 14 pin (some empty pins) plug - thought this had to go to the SAM but there is no spot for it.
2) Green 2 pin plug
3) Brown wire (ground ?)
4) Red wire that ends in a 20amp fuse holder with fuse (+ ?)
I have the Prodigy P2 electronic brake controller.
I also made the mistake to not disconnect the battery when I swapped out the SAM and now the power seats do not work. I will have to check it out in he morning.
What a nightmare.
Any help would be appreciated.
First off, what is the part number of the upgraded rear SAM? We had part A 164 900 54 01 installed (used on the R, ML, and GL class) and it does indeed have the connector for the hitch wiring.
The harness has a multi-pin connector with 4-6 wires going to it that connects to the rear SAM, which is hidden behind some trim on the right side of the spare tire well. If you pull out the spare then remove the plastic liner on the right, it'll be located right underneath the trunk floor. I found a picture of the rear SAM online and highlighted the plug for the trailer harness (see attachment).
The orange (maybe sort of brown) wire with the round crimp terminal at the end is indeed the ground. If you remove the access panel on the right of the trunk (right behind the tail lamps) there is a screw with a nut on it for the grounds (should already have a few ground wires attached to it).
The red wire with the brown 20A fuse fuse holder is the +12V to the bumper plug (battery power). This should be connected to position 70 of the rear fuse box (in the spare tire well) and, as I stated in the first post, will only receive power if the relays are installed in positions U and K.
The remaining connector on the harness goes to the brake controller. As you say this is only a 2-pin connector, one wire is obviously the brake signal from the rear SAM and the other is the powered signal to the bumper plug. You'll need to connect these along with a +12V and Gnd to your brake controller. I'd probably route a length of 16-4 wire from the rear to the driver foot well so that you can have the brake controller accessible while driving.