Abstract: A portable, hand-carriable access device for communicating with a vehicular electronic control unit is coupled to a vehicular communication bus of the vehicle. The device includes a microprocessor, a bus interface unit coupled to the microprocessor and adapted to be coupled to the vehicular communication bus, a memory card port coupled to the microprocessor and adapted to receive a memory card and operative to send script files resident on the memory card to the microprocessor, and a host communication port coupled to the microprocessor and operative to enable data communication between the microprocessor and a remote host computer. The microprocessor is operative to carry out various operations with the vehicular electronic control unit via the vehicular communication bus in accordance with instructions received via the memory card port and/or the host communication port.