Service manual

E4
Introduction
WHAT IS OBD?
2 OBD2
WHAT IS OBD?
The OBD2 Code Reader is designed to work on all OBD 2
compliant vehicles. All 1996 and newer vehicles (cars, light
trucks and SUVs) sold in the United States are OBD 2 compliant.
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 development
of OBD 2, which is on all
1996 and newer vehicles sold in the U.S.
Like its predecessor, OBD 2 was adopted as part of a government
mandate to lower vehicle emissions. But what makes OBD 2 unique
is its universal application for all late model cars and trucks - domestic
and import. This sophisticated program in the vehicle’s main
computer system is designed to detect failures in a range of systems,
and can be accessed through a universal OBD 2 port, which is
usually found under the dashboard. 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 Code Reader, is required to retrieve these codes, which
consumers and professionals use as a starting point for repairs.
To learn more about vehicle Computer Control Systems and
OBD 2, see COMPUTER ENGINE CONTROLS on page 27.