Actron CP9190 manual SAE Publications, GM On-Board Diagnostics

Getting Started

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. Unfortunately, vehicle manufacturers have different interpretations of this standard communications protocol. As a result, the generic OBD II communications scheme varies, depending on the vehicle. 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 that vehicle manufacturers were required to phase in over a three-year period. 2 Beginning in 1994, vehicles with a new engine management computer

( about 10% of each manufacturers fleet ) were supposed to comply with OBD II standards. For 1995, OBD II systems were to appear on about 40% of the new vehicles sold in the United States. Some of the 1994-1995 OBD II systems were not fully compliant, so the Government granted waivers to give manufacturers time to fine-tune their systems. Beginning in 1996, most of the new vehicles sold in the United States were fully OBD II compliant.

The tables below highlight changes for GM, Ford, and Chrysler. If this seems confusing, don’t worry. The Scan Tool makes it easy. Based on the vehicle identification (VIN) information selected during Scan Tool setup, the vehicle is automatically recognized. All you have to do is choose the correct adapter cable and jumper wires (if necessary). Details on adapter cables and jumper wires may be found in Data LInk Connector on page 2-9

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GM On-Board Diagnostics

System	Years	Description
		Most vehicles used the 12-pin ALDL (Assembly Line Data Link)
OBD I Control Module	1981–1995	located under the dash on the driver side. Some 94-95 vehicles
		used the 16-pin OBD II (J1962) data link connector (DLC), but
		use the Historical application software. Refer to the vehicle’s
		Vehicle Emission Control Information label.
OBD II Control Module	1994*-Present	Complies with OBD II regulations and uses the J1962 DLC.

*OBD II system is used on certain 1994-1995 vehicles equipped with a 2.2L, 2.3L, 3.8L, 4.3L or 5.7L engines.

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