Abstract: The present invention provides several apparatus, methods, and computer program products for establishing a data communication link between an interrogation device and the data bus of a vehicle. Specifically, in one embodiment, the present invention provides apparatus, methods, and computer program products that process data transmitted to and from the data bus of a vehicle one bit at a time with minimal delay. The apparatus, methods, and computer program products of this embodiment also prevent propagation of false data to both the data bus and the interrogation device, which is generated by the transmission of data to and from the data bus. The present invention also provides apparatus and methods that reduce the introduction of false data in the form of signal noise onto the data bus of a vehicle when the data bus is not transmitting data to or receiving data from a remote location.