Jimm 5/4/2012The OBDI system is the early generation on-board diagnostic system used for model years up to around 1995. The 1996 and later use the OBD II system for the diagnostics. It provides monitoring of nearly all engine controls, and also some other parts of the vehicle (chassis, body, etc.).
The most useful part of OBD to most drivers is the ability to read information from the vehicle. You can read trouble codes, and even monitor real-time statistics such as RPM, vehicle speed, etc. There are a variety of different devices on the market ranging from basic code scanners to advanced displays that calculate MPG as you drive.
justingg 5/4/2012OBD-I was implemented to help diagnose the earliest Automotive on-board computers by monitoring certain parts of the systems electronically controlled fuel and ignition systems. But individual manufacturers were allowed to design their own diagnostic systems, which made it necessary for mechanics to have different software to access the data from various brand vehicles.
Manufacturers started incorporating OBD-II in various models as early as 1994. All cars built since January 1, 1996 for sale in North America have been required to have OBD-II systems. This system features standardized trouble codes for all makes of cars for most common problems. It also provides almost complete engine control and monitors parts of the chassis, body and accessory devices, as well as the diagnostic control network of the car.
This provides the ability to communicate with Body Control Modules which control things like Anti-Lock Brakes and Traction Control, Active Suspension systems, Anti-Theft systems and many other items not related to engine performance like the earlier systems were confined to.
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