The Main Objectives Of The Obd 2 System Are; Obd 2 Terminology - Innova 3100 Owner's Manual

The Main Objectives of the OBD 2 System are:

To detect degraded and/or failed emissions-related components or
systems that could cause tailpipe emissions to exceed by 1.5
times the Federal Test Procedure (FTP) standard.
To expand emissions-related system monitoring. This includes a
set of computer run diagnostics called Monitors. Monitors perform
diagnostics and testing to verify that all emissions-related
components and/or systems are operating correctly and within the
manufacturer's specifications.
To use a standardized Diagnostic Link Connector (DLC) in all
vehicles. (Before OBD 2, DLCs were of different shapes and
sizes.)
To standardize the code numbers, code definitions and language
used to describe faults. (Before OBD 2, each vehicle manufacturer
used their own code numbers, code definitions and language to
describe the same faults.)
To expand the operation of the Malfunction Indicator Lamp (MIL).
To standardize communication procedures and protocols between
the diagnostic equipment (Scan Tools, Code Readers etc.) and the
vehicle's on-board computer.

OBD 2 Terminology

The following terms and their definitions are related to OBD 2
systems. Read and reference this list as needed to aid in the
understanding of OBD 2 systems.
Powertrain Control Module (PCM) - The PCM is the OBD 2
accepted term for the vehicle's "on-board computer." In addition to
controlling the engine management and emissions systems, the
PCM also participates in controlling the powertrain (transmission)
operation. Most PCMs also have the ability to communicate with
other computers on the vehicle (ABS, ride control, body etc.).
Monitor - Monitors are "diagnostic routines" programmed into the
PCM. The PCM utilizes these programs to run diagnostic tests,
and to monitor operation of the vehicle's emissions-related
components or systems to ensure they are operating correctly and
within the vehicle's manufacturer specifications. Currently, up to
eleven Monitors are used in OBD 2 systems. Additional Monitors
will be added as the OBD 2 system is further developed.
Not all vehicles support all eleven Monitors.
OBD 2
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COMPUTER ENGINE CONTROLS
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