OBD-II is a system used in automobiles to monitor various components of the vehicle, detect malfunctions, and store the information in the vehicle’s on-board computer to be recovered later by a service technician. OBD-II is an acronym for on-board diagnostics; the “II” denotes the second and most current version of this technology.
Features:
• OBD-II uses various sensors throughout the car to provide the
computer, also called an electronic control module (ECM) with
information such as engine and ambient temperatures, vehicle
speed, and so on. The ECM then advances or retards ignition
timing and adds or subtracts fuel accordingly. It also tests the
signals of all attached sensors. When a signal is missing or
out of spec, the OBD-II system illuminates the MIL and stores
a corresponding diagnostic trouble code its memory.
• The information from the OBD-II memory is read through a
connector inside the auto. OBD-II improves on OBD-I not only
in its more sophisticated diagnostic abilities, but also in that it
allows three types of data to be read: trouble codes, real-time
data - the raw sensor information reported to the OBD-II com-
puter, and freeze-frame data - a “snapshot” of sensor data at
the moment the car’s MIL went on. OBD-II codes are read
using cables and software built to communicate with OBD-II
systems. These can take the form of stand-alone units or
software that is installed on a PC. Some are complex models
intended for professional technicians; simpler units are priced
towards hobbyists. |