Interfacing Vector(VN1610) CAN Simulator with an OBD reader (Freematics One+ B)
CAN bus part of the Freematics board is powered through the 12V pin of the OBD connector. The signal is manipulated with a series of cascaded step down converters to fit the power needs of the rest of the circuit. You can follow it from the schematic. 

In short yes you need to connect the 12V pin.