Methods of fabricating large size, high performance multilayer diffraction gratings having a thick substrate that take advantage of reactive ion etching during the fabrication process are provided herein. A human-machine interface is located at the interior assembly and is connected to the in-vehicle communication control via a connective link to communicate at least one human-machine interface signal between the human-machine interface and the in-vehicle communication control. Switch contact elements mounted on the switch actuators and the circuit board provide advantageous positioning of the LED light sources for the switch actuators. The first node has a transceiver and a central processing unit.