Exemplary embodiments of off-board tools (OBTS) may be used in vehicle inspection maintenance programs are provided. The OBT may include a processor, vehicle communication circuitry for linking to a vehicle diagnostic system, host interface circuitry for communicating with a host computer, and voltage determination circuitry for measuring a voltage through the vehicle diagnostic system. The OBT may include logic for storing a communications protocol used to link with a vehicle diagnostic system that is preferably used for re-establishing dropped communications links. In addition, the OBT may contain logic for testing at least one component of a starting and/or charging system of a vehicle. Still other embodiments may include logic for sending unsolicited messages to a host computer. Additional embodiments may include logic for determining the minimum number of messages that must be received by an OBT.