1.1 On-Board Diagnostics (OBD) II
1 General Information
The first generation of On-Board Diagnostics (called OBD I) was
developed by the California Air Resources Board (ARB) and
implemented in 1988 to monitor some of the emission control
components on vehicles. As technology evolved and the desire to
improve the On-Board Diagnostic system increased, a new generation
of On-Board Diagnostic system was developed. This second generation
of On-Board Diagnostic regulations is called “OBD II”.The OBD II
system is designed to monitor emission control systems and key engine
components by performing either continuous or periodic tests of specific
components and vehicle conditions. When a problem is detected, the
OBD II system turns on a warning lamp (MIL) on the vehicle instrument
panel to alert the driver typically by the phrase of “Check Engine” or
“Service Engine Soon”.
The system will also store important information about the detected
malfunction so that a technician can accurately find and fix the problem.
Here below follow
three pieces of such valuable information:
1) Whether the Malfunction Indicator Light (MIL) is commanded ‘on’ or
‘off’;
2) Which, if any, Diagnostic Trouble Codes (DTCs) are stored;
3) Readiness Monitor status.
1.2 Location of the Data Link Connector
The DLC (Data Link Connector or Diagnostic Link Connector) is the
standardized 16-cavity connector where diagnostic code readers
interface with the vehicle’s on-board computer. The DLC is usually
located 12 inches from the center of the instrument panel (dash), under
or around the driver’s side for most vehicles. If Data Link Connector is
