(Retrofit Trailer Coupling Control Unit - AN31.19-P-8080-05LWG)

WARNING: This page is about a different car, the 2023 Mercedes-Benz GLC300, 2022 Mercedes-Benz GLC300, 2021 Mercedes-Benz GLC300, 2020 Mercedes-Benz GLC350e, and 2020 Mercedes-Benz GLC300. However, it is still accessible from the selected car via links, so may be relevant.

Model 253.9 up to 5/31/19

Insert trailer recognition control unit (N28/1) into tab (arrow) and screw down securely using nut (48).
The electrical connectors are connected to the trailer recognition control unit (N28/1) at a later stage.

Courtesy of MERCEDES-BENZ USA