Abstract: A modular connector includes a set of pairs of modular inserts configured to mate with each other to convey electrical signals or power in a structure such as a vehicle. Each pair of modular inserts are coupled to their respective wiring lines and supported by their respective structures. One of each pair of modular inserts is supported by a receptacle shell, while the other is supported by a plug shell. The modular inserts are characterized with removable characterized buttons for cooperation respectively with characterizations slots provided in the receptacle shell and plug shell. The characterization scheme ensures that incorrect modular inserts are not loaded onto the wrong position of the receptacle shell and plug shell. The shields of the wiring lines are grounded to grounding contacts provided in the corresponding modular inserts. The receptacle shell is coupled to a grounding shell supported by the vehicle with the corresponding grounding contacts contacting the grounding shell for grounding.