We do have the written instructions for installing the Vehicle Wiring Harness Kit w/ 4-Pole Trailer Connector and Installation Kit # C59496 which I linked for you, but it is not specific to your 2018 Mercedes-Benz B-250. We have not had a chance to install one on a Mercedes-Benz B-250 ourselves so we do not have a video.
You will need to use the included circuit tester to find the passenger side turn signal wire, driver side turn signal wire, stop light wire, and tail light wire and make... view full answer...