tecnotest EZ-SCAN 4000 Manuel D'utilisation page 60

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EZ-SCAN 4000 ___________________________________________________________________________
OBD-I requires a Malfunction Indicator Lamp (MIL) or check engine light that
illuminates to inform the vehicle operator when an emissions related component or a
monitored system fails. The MIL dash indicator is usually amber or red in colour. Each
OEM manufacturer may call it by a different name.
The computer must have the capability to store Diagnostic Trouble Codes (DTCs).
When a fault occurs, the MIL will illuminate and a DTC is stored in the computer's
memory.
OBD-I requires monitoring of the Oxygen Sensor, EGR System, Fuel Delivery System,
ECM or PCM, and Emission Related Electrical Components.
OBD-II
The California Air Resource Board (CARB) found that by the time an emission system
component fails and causes the MIL to illuminate, the vehicle may have been emitting
excess emissions for some time.
The OEMs had to develop new PCM self-diagnostic strategies in response to increased
diagnostic requirements from the California Air Resource Board (CARB). The latest
regulations developed by CARB and accepted by the Environmental Protection Agency
(EPA) are designated OBD-II.
The Federal Clean Air Act Amendments of 1990 requires that all vehicles sold in the
United States meet OBD-II requirements by the 1996 model year. The first OBD-II
systems appeared on selected vehicle types in 1994.
Some important OBD-II requirements are: Vehicle service information available to all
technicians; Standardization of Terms: Use of SAE J-1930 recommended terms; OBD-II
requires a common Diagnostic Link Connector (DLC) and specifies its location in the
vehicle; Generic scan tool; Generic emission related Diagnostic Trouble Codes (DTC);
and a very specific Malfunction Indicator Light (MIL) illumination protocol.
One very important part of the OBD-II requirements is that technical service
information for emissions related components and systems, which could affect the
vehicle's emission levels, will be available to all technicians; not just OEM dealership
technicians. This will allow all technicians to better understand how the systems
recognize faults and set the DTCs. The technician can now make a repair and verify the
repair by exactly duplicating the criteria that is required for the DTC to be set.
58 OPERATING INSTRUCTIONS