> Is there a generic item that indicates ability to read the extended
> parameters?

There are a few different protocols when dealing with different
manufacturers. If you're into DIY check out
http://www.obddiag.net/allpro.html for a cheap kit. Also, ELM sells
preprogrammed PICs. They also have example circuits in the data
sheets. See http://www.elmelectronics.com/DSheets/ELM327DS.pdf . If
you want a fully built solution go to scantool.net (Russell mentioned
recently releasing their new DIP interface board, but they also have
complete units).
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