Abstract: A portable system for powering and testing the electrical circuits of a vehicle comprising a source of electrical power adapted to power the system and to provide electrical power to the vehicle. A power connector is adapted to quickly connect/disconnect the system to/from the electrical system of the vehicle. A diagnostic connector is adapted to quickly connect/disconnect the system to/from the electrical circuits of the vehicle being tested. A portable, low-power, sealed computing device is adapted to perform testing on the electrical circuits of the vehicle. A vehicle-communications interface is in electrical communication with the computing device and diagnostic connector that is adapted to provide electrical interface between the computing device and the electrical circuits of the vehicle.