Introduction To On-Board Diagnostics; Sae Publications - Actron CP9180 Manual

Getting Started

Introduction to On-Board Diagnostics

OBD II
On-board diagnostics version II (OBD II) is a system that the Society of
Automotive Engineers (SAE) developed to standardize automotive
electronic diagnosis.
Beginning in 1996, most new vehicles sold in the United States were
fully OBD II compliant.
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Technicians can now use the same tool to test any OBD II
compliant vehicle without special adapters. SAE established
guidelines that provide:
❒
A universal connector, called the DLC, with dedicated pin
assignments.
❒
A standard location for the DLC, visible under the dash on driver's
side.
❒
A standard list of diagnostic trouble codes (DTCs) used by all
manufacturers.
❒
A standard list of parameter identification (PID) data used by all
manufacturers.
❒
Ability for vehicle systems to record operating conditions when a
fault occurs.
❒
Expanded diagnostic capabilities that records a code whenever a
condition occurs that affects vehicle emissions.
❒
Ability to clear stored codes from the vehicle's memory with a
Scan Tool.

SAE Publications

SAE has published hundreds of pages of text defining a standard
communication protocol that establishes hardware, software, and
circuit parameters of OBD II systems.
• SAE publishes recommendations, not laws, but the Environmental
Protection Agency (EPA) and California Air Resources Board
(CARB) made many of SAE's recommendations legal requirements.
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