Actron 9640 Manuel D’Utilisation

In addition, SAE has published hundreds of pages of text defining a standard 

communications protocol that establishes the 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 used will vary, 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. 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 

granted waivers to give manufacturers time to fine-tune their systems. 

Beginning in 1996, most of the new vehicles sold in the USA were fully OBD II 

compliant.

The Data Link Connector (DLC) allows the scan tool to communicate with the 

vehicle’s computer(s). Before OBD II, manufacturers used different data link 

connectors to communicate with the vehicle. The proper DLC adapter cable 

must be used to connect the tool to the vehicle. Also, the vehicle’s DLC may be 

found in several different places and have many different configurations. The 

following describes the DLCs used by Ford, GM and Chrysler. The DLC location 

and types for domestic vehicles can be looked up in the charts in “Appendix