That is really reassuring, thanks for confirming that info. I think I am just about ready to get all the parts ordered. I did read through the ELM327 chip diagram circuit and like its all-in-one ability. Didn't really like the price though... ~$40 shipped.
I think I'm going with the ELM320 as it is all I need. I was looking at the connection between the obd port and the special "interface". Do you recommend an OBD2 to DB9F cable or is a OBD2 plug with only needed wires ok? was worried about interference and gauge.
Also do you recommend hooking the arduino to +12v/signal ground (on all the time) or switched +12v/signal ground (like cd player)?
Happy 4th of july!