OBD2 & 1 Tool Owners Manual

One of the most exciting improvements in the automobile industry was the addition of on-board diagnostics (OBD) on vehicles, or in more basic terms, the computer that activates the vehicle’s “CHECK ENGINE” light. OBD 1 was designed to monitor manufacturer-specific systems on vehicles built from 1981 to 1995. Then came the develop- ment of OBD 2, which is on all 1996 cars and light trucks sold in the United States. These systems are part of a government mandate to lower vehicle emissions. The sophisticated programs in the vehicle’s on-board computer system are designed to detect failures in a range of vehicle systems. Diagnostic information can be accessed through a Data Link Connector test port specifically designed for this purpose. For all OBD systems, if a problem is found, the computer turns on the “CHECK ENGINE” light to warn the driver, and sets a Diagnostic Trouble Code (DTC) to identify where the problem occurred. A special diagnostic tool, such as the OBD2 & 1 Tool, is required to retrieve these codes, which consumers and professionals use as a starting point for repairs.
This manual describes common test procedures used by experienced service technicians. Many test procedures require precautions to avoid accidents that can result in personal injury, and/or damage to your vehicle or test equipment. Always read your vehicle's service manual and follow its safety precautions before and during any test or service procedure.

Source