I hope I am posting correctly. I have a 2000 ML320. I am installing a new tow hitch. The vehicle is prewired for a tow hitch harness that plugs directly into the prewired connector. I have watched several videos regarding the installation of the tow hitch harness. The harness part number is either 15388988, or 163540USA4. I have seen pictures of this part with a black box and others without the box. It is my understanding the harness without the black box is a newer version. In any event, both apparently work. Does anyone have one of these harnesses that is in decent condition? I have found two on eBay, each at $150, but the same seller is unresponsive. If you have one, I am happy to pay a fair price.

This isnthe harness, bracket and plug.

Here is a picture of some numbers related to the harness.

 

moved to W163 forum...

 

I wanted to post my resolution. After reading virtually everything posted on this platform regarding ML320 and ML350 tow hitch harnesses, I was confident I could tackle this matter myself. Thanks to everyone who contributed to earlier threads on the same subject. Okay. Here we go. I decided I did not want to splice into my existing pre-wired harness. The harness is accessible through the driver side rear panel or by removing the bumper and removing the first vent panel. To gain access and to have space to work, I loosened the back panel so I could pull it back several inches and I removed my rear bumper. You have to search for the harness but eventually I found it. The connector at the end of the harness contains female connector pins. The connector is made by TE Connectivity for Mercedes, and it is still available through Mercedes or through TE Connectivity's distributors. To get a clearer look at the connector and pins, I went to a local Pick Your Part and pulled two harnesses from ML320s. I broke apart one of the connectors to see how the connectors were secured. Finding the connector that connects to my prewired harness connector, and the male pins for that connector, was a challenge. Previous postings stated that the connector was available through a company name Crutchfield. I called them and their technical support team rep told me they only had one 16 pin connector so I thought I'd take a chance. It arrived pinned with male connectors, the wiring was all of the same size and only some of the same wire colors that were in my prewired harness. The connector was not made by Crutchfield but by Metra. I watched some YouTube videos on depinning connectors and eventually figured out how to depin the Metra connector. I then called Metra to see if they sold the pins for the connector separately. They said they did not. I searched more forum postings and someone had posted that there were pins almost identical to the ones needed and all you had to do was flatten the two butterfly shaped sides and trim them a little to fit them into the connector. A link was provided so I bought 25 male and female pins. I had also bought online the male and female harnesses that are for a ML320 radio. Mercedes uses the same harnesses for the tow hitch harness and the radio harness. Although more of the same Mercedes wire colors were used in these harnesses, the ground and hot wires were a thinner gage. I depinned the male pinned harness, and then repinned it matching the color and wire sizes so it was identical to my pre-wired harness. My idea was to simply connect it to my existing harness, and then wire in a CURT or Tekonsha brake light controller and be finished. I included a picture of the the harness I made below. I connected my home made harness to my existing harness, and fed the wires into the rear driver side panel area. I then bought a Tekonsha brake light controller. During this entire time I continued to watch YouTube videos and in one of them the person highly recommended remaining steadfast in finding and installing the OEM harness since it was plug-and-play, and it came with a convenient 7-way plug and mounting bracket that bolted up to pre-drilled holes in the Mercedes frame. Fortunately, depending on how you look it at, one became available on eBay so I bought it. It arrived the same time as my Tekonsha controller. I decided to connect the OEM tow hitch harness to see if it worked so I unpluged my home made harness, connected the OEM harness, installed the 25 amp fuse for the 12V wire and everything worked perfectly. If anyone wants to know the part number for the harnesses or pins, let me know and I will be happy to provide them.