1. Safety Precautions and Warnings
To prevent personal injury or damage to vehicles and/or the scan tool, please read this
manual rst and follow the following safety instructions whenever working on a vehicle:
• Always perform automotive testing in a safe environment.
• Wear safety eye protection that meets ANSI standards.
• Keep clothing, hair, hands, tools, test equipment, etc, away from all moving or hot
engine parts.
• Operate the vehicle in a well-ventilated work area; Exhaust gases are poisonous.
• Put blocks on drive wheels and never leave vehicle unattended while running tests.
• Use extreme caution when working around the ignition coil, distributor cap, ignition
wires and spark plugs. These components create hazardous voltages when the engine is
running.
• Put transmission in PARK (for automatic transmission) or NEUTRAL (for manual
transmission) and make sure the parking brake is engaged.
• Keep a re extinguisher suitable for gasoline/chemical/ electrical res nearby.
• Don’t connect or disconnect any test equipment with ignition on or engine running.
• Keep the scan tool dry, clean and free from oil, water and grease. Use a mild detergent
on a clean cloth to clean the outside of the Scan Tool, when necessary.
2. General Information
2.1 On-Board-Diagnostics (OBD) II
The rst generation of On-Board Diagnostic (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 OBD I system increased, a new generation of On-Board Diagnostics 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 specic 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
nd and x the problem. Here below follow three pieces of such valuable information:
• Whether the Malfunction Indicator Light (MIL) is commanded 'on' or 'off';
• Which, if any, Diagnostic Trouble Codes (DTCs) are stored;
• Readiness Monitor Status.
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