On my 2001 Patriot my ECM diagnostic port was, as Carl stated, behind dash more centrally located behind dash radio.  I laid on my back in front of driver's seat looked up and towards the radio and there it was.
I was able to free it up by snipping a few zip ties and pulling it down for better access.  It was a 6-pin diagnostic port (1990's to early 2000's).  Not the newer 9-pin (early 2000's to present).
Good luck!